ICU-20857 Update version numbers to 66.1
diff --git a/icu4c/readme.html b/icu4c/readme.html
index e991f14..a42a2c9 100644
--- a/icu4c/readme.html
+++ b/icu4c/readme.html
@@ -3,7 +3,7 @@
 
 <html lang="en-US" xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US">
   <head>
-    <title>ReadMe for ICU 65.1</title>
+    <title>ReadMe for ICU 66.1</title>
     <meta name="COPYRIGHT" content=
     "Copyright (C) 2016 and later: Unicode, Inc. and others. License &amp; terms of use: http://www.unicode.org/copyright.html"/>
     <!-- meta name="COPYRIGHT" content=
@@ -23,8 +23,8 @@
         milestone - if the release note is a milestone release
 -->
 
-  <body>
-  <!-- <body class="rc"> -->
+  <!-- <body> -->
+  <body class="rc">
     <p class="only-draft"><b>Note:</b> This is a draft readme.</p>
 
     <h1>
@@ -32,7 +32,7 @@
       International Components for Unicode<br/>
       <span class="only-rc">Release Candidate</span>
       <span class="only-milestone">(Milestone Release)</span>
-      <abbr title="International Components for Unicode">ICU</abbr> 65.1 ReadMe
+      <abbr title="International Components for Unicode">ICU</abbr> 66.1 ReadMe
     </h1>
 
     <!-- Shouldn't need to comment/uncomment this paragraph, just change the body class -->
@@ -44,7 +44,7 @@
     <p class="note only-rc">This is a release candidate version of ICU4C.
       It is not recommended for production use.</p>
 
-    <p>Last updated: 2019-Sept-16<br/>
+    <p>Last updated: 2019-Oct-09<br/>
       Copyright &copy; 2016 and later: Unicode, Inc. and others. License &amp; terms of use:
       <a href="http://www.unicode.org/copyright.html">http://www.unicode.org/copyright.html</a><br/>
       Copyright &copy; 1997-2016 International Business Machines Corporation and others.
@@ -233,7 +233,7 @@
 
     <h2><a name="News" href="#News" id="News">What Is New In This Release?</a></h2>
 
-    <p>See the <a href="http://site.icu-project.org/download/65">ICU 65 download page</a>
+    <p>See the <a href="http://site.icu-project.org/download/66">ICU 66 download page</a>
     for an overview of this release, important changes, new features, bug fixes, known issues,
     changes to supported platforms and build environments,
     and migration issues for existing applications migrating from previous ICU releases.</p>
diff --git a/icu4c/source/common/common.vcxproj b/icu4c/source/common/common.vcxproj
index 54eb011..8761d2f 100644
--- a/icu4c/source/common/common.vcxproj
+++ b/icu4c/source/common/common.vcxproj
@@ -74,7 +74,7 @@
       <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc65d.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icuucd.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuucd.lib</ImportLibrary>
     </Link>
@@ -86,7 +86,7 @@
       <FunctionLevelLinking>true</FunctionLevelLinking>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc65.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icuuc.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuuc.lib</ImportLibrary>
     </Link>
diff --git a/icu4c/source/common/common_uwp.vcxproj b/icu4c/source/common/common_uwp.vcxproj
index 8469178..f9fe936 100644
--- a/icu4c/source/common/common_uwp.vcxproj
+++ b/icu4c/source/common/common_uwp.vcxproj
@@ -129,7 +129,7 @@
     <Link>
       <EnableCOMDATFolding>true</EnableCOMDATFolding>
       <AdditionalDependencies>vccorlib.lib;msvcrt.lib;vcruntime.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc65.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icuuc.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuuc.lib</ImportLibrary>
     </Link>
@@ -152,7 +152,7 @@
     <Link>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <AdditionalDependencies>vccorlibd.lib;msvcrtd.lib;vcruntimed.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc65d.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuuc66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icuucd.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuucd.lib</ImportLibrary>
     </Link>
diff --git a/icu4c/source/common/unicode/uvernum.h b/icu4c/source/common/unicode/uvernum.h
index 0923c1d..f5d6497 100644
--- a/icu4c/source/common/unicode/uvernum.h
+++ b/icu4c/source/common/unicode/uvernum.h
@@ -60,7 +60,7 @@
  *  This value will change in the subsequent releases of ICU
  *  @stable ICU 2.4
  */
-#define U_ICU_VERSION_MAJOR_NUM 65
+#define U_ICU_VERSION_MAJOR_NUM 66
 
 /** The current ICU minor version as an integer.
  *  This value will change in the subsequent releases of ICU
@@ -86,7 +86,7 @@
  *  This value will change in the subsequent releases of ICU
  *  @stable ICU 2.6
  */
-#define U_ICU_VERSION_SUFFIX _65
+#define U_ICU_VERSION_SUFFIX _66
 
 /**
  * \def U_DEF2_ICU_ENTRY_POINT_RENAME
@@ -139,7 +139,7 @@
  *  This value will change in the subsequent releases of ICU
  *  @stable ICU 2.4
  */
-#define U_ICU_VERSION "65.1"
+#define U_ICU_VERSION "66.1"
 
 /**
  * The current ICU library major version number as a string, for library name suffixes.
@@ -152,13 +152,13 @@
  *
  * @stable ICU 2.6
  */
-#define U_ICU_VERSION_SHORT "65"
+#define U_ICU_VERSION_SHORT "66"
 
 #ifndef U_HIDE_INTERNAL_API
 /** Data version in ICU4C.
  * @internal ICU 4.4 Internal Use Only
  **/
-#define U_ICU_DATA_VERSION "65.1"
+#define U_ICU_DATA_VERSION "66.1"
 #endif  /* U_HIDE_INTERNAL_API */
 
 /*===========================================================================
diff --git a/icu4c/source/configure b/icu4c/source/configure
index 35c8c56..d92d6ee 100755
--- a/icu4c/source/configure
+++ b/icu4c/source/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for ICU 65.1.
+# Generated by GNU Autoconf 2.69 for ICU 66.1.
 #
 # Report bugs to <http://icu-project.org/bugs>.
 #
@@ -582,8 +582,8 @@
 # Identity of this package.
 PACKAGE_NAME='ICU'
 PACKAGE_TARNAME='International Components for Unicode'
-PACKAGE_VERSION='65.1'
-PACKAGE_STRING='ICU 65.1'
+PACKAGE_VERSION='66.1'
+PACKAGE_STRING='ICU 66.1'
 PACKAGE_BUGREPORT='http://icu-project.org/bugs'
 PACKAGE_URL='http://icu-project.org'
 
@@ -1362,7 +1362,7 @@
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures ICU 65.1 to adapt to many kinds of systems.
+\`configure' configures ICU 66.1 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1428,7 +1428,7 @@
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of ICU 65.1:";;
+     short | recursive ) echo "Configuration of ICU 66.1:";;
    esac
   cat <<\_ACEOF
 
@@ -1566,7 +1566,7 @@
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-ICU configure 65.1
+ICU configure 66.1
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2312,7 +2312,7 @@
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by ICU $as_me 65.1, which was
+It was created by ICU $as_me 66.1, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -8532,7 +8532,7 @@
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by ICU $as_me 65.1, which was
+This file was extended by ICU $as_me 66.1, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -8586,7 +8586,7 @@
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-ICU config.status 65.1
+ICU config.status 66.1
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 
diff --git a/icu4c/source/data/makedata.mak b/icu4c/source/data/makedata.mak
index dfd6273..951f76f 100644
--- a/icu4c/source/data/makedata.mak
+++ b/icu4c/source/data/makedata.mak
@@ -12,11 +12,11 @@
 
 ##############################################################################
 # Keep the following in sync with the version - see common/unicode/uvernum.h
-U_ICUDATA_NAME=icudt65
+U_ICUDATA_NAME=icudt66
 ##############################################################################
 !IF "$(UWP)" == "UWP"
 # Optionally change the name of the data file for the UWP version.
-U_ICUDATA_NAME=icudt65
+U_ICUDATA_NAME=icudt66
 !ENDIF
 U_ICUDATA_ENDIAN_SUFFIX=l
 UNICODE_VERSION=12.1
diff --git a/icu4c/source/data/misc/icuver.txt b/icu4c/source/data/misc/icuver.txt
index 69e244c..3d5c318 100644
--- a/icu4c/source/data/misc/icuver.txt
+++ b/icu4c/source/data/misc/icuver.txt
@@ -8,6 +8,6 @@
 // ***************************************************************************
 
 icuver:table(nofallback){ 
-    DataVersion { "65.1.0.0" }
-    ICUVersion  { "65.1.0.0" }
+    DataVersion { "66.1.0.0" }
+    ICUVersion  { "66.1.0.0" }
 }
diff --git a/icu4c/source/i18n/i18n.vcxproj b/icu4c/source/i18n/i18n.vcxproj
index e939eb5..5c6760d 100644
--- a/icu4c/source/i18n/i18n.vcxproj
+++ b/icu4c/source/i18n/i18n.vcxproj
@@ -76,7 +76,7 @@
     </ClCompile>
     <Link>
       <AdditionalDependencies>icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuin65d.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuin66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icuind.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuind.lib</ImportLibrary>
     </Link>
@@ -89,7 +89,7 @@
     </ClCompile>
     <Link>
       <AdditionalDependencies>icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuin65.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuin66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icuin.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuin.lib</ImportLibrary>
     </Link>
diff --git a/icu4c/source/i18n/i18n_uwp.vcxproj b/icu4c/source/i18n/i18n_uwp.vcxproj
index 24ac8f3..989cef8 100644
--- a/icu4c/source/i18n/i18n_uwp.vcxproj
+++ b/icu4c/source/i18n/i18n_uwp.vcxproj
@@ -190,7 +190,7 @@
       <ProgramDataBaseFileName>.\x86\ReleaseUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin32uwp\icuin65.dll</OutputFile>
+      <OutputFile>..\..\bin32uwp\icuin66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\lib32uwp\icuin.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\lib32uwp\icuin.lib</ImportLibrary>
       <AdditionalDependencies>..\..\lib32uwp\icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -207,7 +207,7 @@
       <ProgramDataBaseFileName>.\x86\DebugUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin32uwp\icuin65d.dll</OutputFile>
+      <OutputFile>..\..\bin32uwp\icuin66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\lib32uwp\icuind.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\lib32uwp\icuind.lib</ImportLibrary>
       <AdditionalDependencies>..\..\lib32uwp\icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -224,7 +224,7 @@
       <ProgramDataBaseFileName>.\x64\ReleaseUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin64uwp\icuin65.dll</OutputFile>
+      <OutputFile>..\..\bin64uwp\icuin66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\lib64uwp\icuin.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\lib64uwp\icuin.lib</ImportLibrary>
       <AdditionalDependencies>..\..\lib64uwp\icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -241,7 +241,7 @@
       <ProgramDataBaseFileName>.\x64\DebugUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin64uwp\icuin65d.dll</OutputFile>
+      <OutputFile>..\..\bin64uwp\icuin66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\lib64uwp\icuind.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\lib64uwp\icuind.lib</ImportLibrary>
       <AdditionalDependencies>..\..\lib64uwp\icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -258,7 +258,7 @@
       <ProgramDataBaseFileName>.\ARM\ReleaseUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\binARMuwp\icuin65.dll</OutputFile>
+      <OutputFile>..\..\binARMuwp\icuin66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\libARMuwp\icuin.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\libARMuwp\icuin.lib</ImportLibrary>
       <AdditionalDependencies>..\..\libARMuwp\icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -275,7 +275,7 @@
       <ProgramDataBaseFileName>.\ARM\DebugUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\binARMuwp\icuin65d.dll</OutputFile>
+      <OutputFile>..\..\binARMuwp\icuin66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\libARMuwp\icuind.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\libARMuwp\icuind.lib</ImportLibrary>
       <AdditionalDependencies>..\..\libARMuwp\icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -292,7 +292,7 @@
       <ProgramDataBaseFileName>.\ARM64\ReleaseUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\binARM64uwp\icuin65.dll</OutputFile>
+      <OutputFile>..\..\binARM64uwp\icuin66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\libARM64uwp\icuin.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\libARM64uwp\icuin.lib</ImportLibrary>
       <AdditionalDependencies>..\..\libARM64uwp\icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -309,7 +309,7 @@
       <ProgramDataBaseFileName>.\ARM64\DebugUWP/</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\binARM64uwp\icuin65d.dll</OutputFile>
+      <OutputFile>..\..\binARM64uwp\icuin66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\libARM64uwp\icuind.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\libARM64uwp\icuind.lib</ImportLibrary>
       <AdditionalDependencies>..\..\libARM64uwp\icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
diff --git a/icu4c/source/io/io.vcxproj b/icu4c/source/io/io.vcxproj
index 3fca55f..fa45bb4 100644
--- a/icu4c/source/io/io.vcxproj
+++ b/icu4c/source/io/io.vcxproj
@@ -76,7 +76,7 @@
     </ClCompile>
     <Link>
       <GenerateDebugInformation>true</GenerateDebugInformation>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuio65d.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuio66d.dll</OutputFile>
       <ProgramDatabaseFile>..\..\$(IcuLibOutputDir)\icuiod.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuiod.lib</ImportLibrary>
       <AdditionalDependencies>icuucd.lib;icuind.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -89,7 +89,7 @@
       <FunctionLevelLinking>true</FunctionLevelLinking>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\$(IcuBinOutputDir)\icuio65.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icuio66.dll</OutputFile>
       <ProgramDatabaseFile>..\..\$(IcuLibOutputDir)\icuio.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icuio.lib</ImportLibrary>
       <AdditionalDependencies>icuuc.lib;icuin.lib;%(AdditionalDependencies)</AdditionalDependencies>
diff --git a/icu4c/source/layoutex/layoutex.vcxproj b/icu4c/source/layoutex/layoutex.vcxproj
index efa1a33..eba32b0 100644
--- a/icu4c/source/layoutex/layoutex.vcxproj
+++ b/icu4c/source/layoutex/layoutex.vcxproj
@@ -70,7 +70,7 @@
       <CompileAs>Default</CompileAs>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin\iculx65.dll</OutputFile>
+      <OutputFile>..\..\bin\iculx66.dll</OutputFile>
       <AdditionalDependencies>icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <AdditionalLibraryDirectories>.\..\..\lib;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
       <ProgramDatabaseFile>.\..\..\lib\iculx.pdb</ProgramDatabaseFile>
@@ -95,7 +95,7 @@
       <CompileAs>Default</CompileAs>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin\iculx65d.dll</OutputFile>
+      <OutputFile>..\..\bin\iculx66d.dll</OutputFile>
       <AdditionalDependencies>icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <AdditionalLibraryDirectories>.\..\..\lib;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
       <GenerateDebugInformation>true</GenerateDebugInformation>
@@ -120,7 +120,7 @@
       <CompileAs>Default</CompileAs>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin64\iculx65.dll</OutputFile>
+      <OutputFile>..\..\bin64\iculx66.dll</OutputFile>
       <AdditionalDependencies>icuuc.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <AdditionalLibraryDirectories>.\..\..\lib64;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
       <ProgramDatabaseFile>.\..\..\lib64\iculx.pdb</ProgramDatabaseFile>
@@ -143,7 +143,7 @@
       <CompileAs>Default</CompileAs>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\bin64\iculx65d.dll</OutputFile>
+      <OutputFile>..\..\bin64\iculx66d.dll</OutputFile>
       <AdditionalDependencies>icuucd.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <AdditionalLibraryDirectories>.\..\..\lib64;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
       <GenerateDebugInformation>true</GenerateDebugInformation>
diff --git a/icu4c/source/stubdata/stubdata.vcxproj b/icu4c/source/stubdata/stubdata.vcxproj
index 751bba0..0c48623 100644
--- a/icu4c/source/stubdata/stubdata.vcxproj
+++ b/icu4c/source/stubdata/stubdata.vcxproj
@@ -72,7 +72,7 @@
       <SetChecksum>true</SetChecksum>
       <TurnOffAssemblyGeneration>true</TurnOffAssemblyGeneration>
       <!-- Note: stubdata is somewhat odd in that it doesn't suffix the Debug output DLL/LIB with a "d" like common/i18n/etc. -->
-      <OutputFile>..\..\$(IcuBinOutputDir)\icudt65.dll</OutputFile>
+      <OutputFile>..\..\$(IcuBinOutputDir)\icudt66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\$(IcuLibOutputDir)\icudt.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\$(IcuLibOutputDir)\icudt.lib</ImportLibrary>
     </Link>
diff --git a/icu4c/source/tools/ctestfw/ctestfw.vcxproj b/icu4c/source/tools/ctestfw/ctestfw.vcxproj
index b3b1895..1a685ed 100644
--- a/icu4c/source/tools/ctestfw/ctestfw.vcxproj
+++ b/icu4c/source/tools/ctestfw/ctestfw.vcxproj
@@ -69,7 +69,7 @@
       <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\..\$(IcuBinOutputDir)\icutest65d.exe</OutputFile>
+      <OutputFile>..\..\..\$(IcuBinOutputDir)\icutest66d.exe</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\$(IcuLibOutputDir)\icutestd.pdb</ProgramDatabaseFile>
       <ImportLibrary>.\..\..\..\$(IcuLibOutputDir)\icutestd.lib</ImportLibrary>
       <AdditionalDependencies>icuucd.lib;icutud.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -82,7 +82,7 @@
       <FunctionLevelLinking>true</FunctionLevelLinking>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\..\$(IcuBinOutputDir)\icutest65.exe</OutputFile>
+      <OutputFile>..\..\..\$(IcuBinOutputDir)\icutest66.exe</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\$(IcuLibOutputDir)\icutest.pdb</ProgramDatabaseFile>
       <ImportLibrary>.\..\..\..\$(IcuLibOutputDir)\icutest.lib</ImportLibrary>
       <AdditionalDependencies>icuuc.lib;icutu.lib;%(AdditionalDependencies)</AdditionalDependencies>
diff --git a/icu4c/source/tools/toolutil/toolutil.vcxproj b/icu4c/source/tools/toolutil/toolutil.vcxproj
index d6ab104..9a4f250 100644
--- a/icu4c/source/tools/toolutil/toolutil.vcxproj
+++ b/icu4c/source/tools/toolutil/toolutil.vcxproj
@@ -90,7 +90,7 @@
       <TypeLibraryName>.\..\..\..\lib\icutu.tlb</TypeLibraryName>
     </Midl>
     <Link>
-      <OutputFile>..\..\..\bin\icutu65.dll</OutputFile>
+      <OutputFile>..\..\..\bin\icutu66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\lib\icutu.pdb</ProgramDatabaseFile>
       <DataExecutionPrevention>
       </DataExecutionPrevention>
@@ -102,7 +102,7 @@
       <TypeLibraryName>.\..\..\..\lib\icutud.tlb</TypeLibraryName>
     </Midl>
     <Link>
-      <OutputFile>..\..\..\bin\icutu65d.dll</OutputFile>
+      <OutputFile>..\..\..\bin\icutu66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\lib\icutud.pdb</ProgramDatabaseFile>
       <DataExecutionPrevention>
       </DataExecutionPrevention>
@@ -129,7 +129,7 @@
       <WholeProgramOptimization>true</WholeProgramOptimization>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\..\bin64\icutu65.dll</OutputFile>
+      <OutputFile>..\..\..\bin64\icutu66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\lib64\icutu.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\..\lib64\icutu.lib</ImportLibrary>
     </Link>
@@ -139,7 +139,7 @@
       <TypeLibraryName>.\..\..\..\lib64\icutud.tlb</TypeLibraryName>
     </Midl>
     <Link>
-      <OutputFile>..\..\..\bin64\icutu65d.dll</OutputFile>
+      <OutputFile>..\..\..\bin64\icutu66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\lib64\icutud.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\..\lib64\icutud.lib</ImportLibrary>
     </Link>
@@ -160,7 +160,7 @@
       <TypeLibraryName>..\..\..\libARM\icutu.tlb</TypeLibraryName>
     </Midl>
     <Link>
-      <OutputFile>..\..\..\binARM\icutu65.dll</OutputFile>
+      <OutputFile>..\..\..\binARM\icutu66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\libARM\icutu.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\..\libARM\icutu.lib</ImportLibrary>
     </Link>
@@ -173,7 +173,7 @@
       <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\..\binARM\icutu65d.dll</OutputFile>
+      <OutputFile>..\..\..\binARM\icutu66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\libARM\icutud.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\..\libARM\icutud.lib</ImportLibrary>
     </Link>
@@ -194,7 +194,7 @@
       <TypeLibraryName>.\..\..\..\libARM64\icutu.tlb</TypeLibraryName>
     </Midl>
     <Link>
-      <OutputFile>..\..\..\binARM64\icutu65.dll</OutputFile>
+      <OutputFile>..\..\..\binARM64\icutu66.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\libARM64\icutu.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\..\libARM64\icutu.lib</ImportLibrary>
     </Link>
@@ -207,7 +207,7 @@
       <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
     </ClCompile>
     <Link>
-      <OutputFile>..\..\..\binARM64\icutu65d.dll</OutputFile>
+      <OutputFile>..\..\..\binARM64\icutu66d.dll</OutputFile>
       <ProgramDatabaseFile>.\..\..\..\libARM64\icutud.pdb</ProgramDatabaseFile>
       <ImportLibrary>..\..\..\libARM64\icutud.lib</ImportLibrary>
     </Link>
diff --git a/icu4j/build.properties b/icu4j/build.properties
index 56c712d..ac9dd49 100644
--- a/icu4j/build.properties
+++ b/icu4j/build.properties
@@ -4,9 +4,9 @@
 #* Copyright (C) 2009-2016, International Business Machines Corporation and    *
 #* others. All Rights Reserved.                                                *
 #*******************************************************************************
-api.report.version = 65
-api.report.prev.version = 64
-release.file.ver = 65_1
-api.doc.version = 65.1
-maven.pom.ver = 65.1
+api.report.version = 66
+api.report.prev.version = 65
+release.file.ver = 66rc
+api.doc.version = 66 Release Candidate
+maven.pom.ver = 66.1-SNAPSHOT
 
diff --git a/icu4j/eclipse-build/build.properties b/icu4j/eclipse-build/build.properties
index a8a357c..46dfb8c 100644
--- a/icu4j/eclipse-build/build.properties
+++ b/icu4j/eclipse-build/build.properties
@@ -4,6 +4,6 @@
 #* Copyright (C) 2010-2016, International Business Machines Corporation and    *
 #* others. All Rights Reserved.                                                *
 #*******************************************************************************
-icu4j.plugin.impl.version.string=65.1.0
+icu4j.plugin.impl.version.string=66.1.0
 copyright.eclipse=(C) 2016 and later: Unicode, Inc. and others. License & terms of use: http://www.unicode.org/copyright.html#License
-icu4j.data.version.number=65
+icu4j.data.version.number=66
diff --git a/icu4j/main/classes/core/src/com/ibm/icu/util/VersionInfo.java b/icu4j/main/classes/core/src/com/ibm/icu/util/VersionInfo.java
index 59dc3f8..dbbed9a 100644
--- a/icu4j/main/classes/core/src/com/ibm/icu/util/VersionInfo.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/util/VersionInfo.java
@@ -206,7 +206,7 @@
      * @deprecated This API is ICU internal only.
      */
     @Deprecated
-    public static final String ICU_DATA_VERSION_PATH = "65b";
+    public static final String ICU_DATA_VERSION_PATH = "66b";
 
     /**
      * Data version in ICU4J.
@@ -588,7 +588,7 @@
         UNICODE_12_0   = getInstance(12, 0, 0, 0);
         UNICODE_12_1   = getInstance(12, 1, 0, 0);
 
-        ICU_VERSION   = getInstance(65, 1, 0, 0);
+        ICU_VERSION   = getInstance(66, 1, 0, 0);
         ICU_DATA_VERSION = ICU_VERSION;
         UNICODE_VERSION = UNICODE_12_1;
 
diff --git a/icu4j/main/shared/build/common.properties b/icu4j/main/shared/build/common.properties
index 69d0a7d..17ea1fd 100644
--- a/icu4j/main/shared/build/common.properties
+++ b/icu4j/main/shared/build/common.properties
@@ -6,9 +6,9 @@
 #*******************************************************************************
 
 # Version numbers, etc.
-icu4j.spec.version = 65
-icu4j.impl.version = 65.1
-icu4j.data.version = 65
+icu4j.spec.version = 66
+icu4j.impl.version = 66.1
+icu4j.data.version = 66
 default.exec.env = JavaSE-1.7
 
 copyright = \u00A9 2016 and later: Unicode, Inc. and others. License & terms of use: http://www.unicode.org/copyright.html#License
diff --git a/icu4j/main/shared/data/icudata.jar b/icu4j/main/shared/data/icudata.jar
index 8f974a1..2918499 100644
--- a/icu4j/main/shared/data/icudata.jar
+++ b/icu4j/main/shared/data/icudata.jar
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:fd707bc2310c8fbd2fac9b63492f171934b276dc2d6593b8df7c453adcaf512f
-size 12967319
+oid sha256:f561d34f6dfd8451abd0b8085b71a241517c885dcc61d9348015be945e324337
+size 12967292
diff --git a/icu4j/main/shared/data/icutzdata.jar b/icu4j/main/shared/data/icutzdata.jar
index 1219e5f..0b65336 100644
--- a/icu4j/main/shared/data/icutzdata.jar
+++ b/icu4j/main/shared/data/icutzdata.jar
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:43cba68295238f4d1ecf7e5da88974de86ca942a03e9c195522ebc421c6185ef
+oid sha256:29d4351d79b7fd577b3db4c358ca5059cf35352916c1c9186a59b30eb68b95ec
 size 94279
diff --git a/icu4j/main/shared/data/testdata.jar b/icu4j/main/shared/data/testdata.jar
index 50307fe..c24d34c 100644
--- a/icu4j/main/shared/data/testdata.jar
+++ b/icu4j/main/shared/data/testdata.jar
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:453deb3e240c6f22d674e04e158f08cbb56864ea0da525a0316f6fdbf3f86320
-size 723409
+oid sha256:eceff97d6784170a592cfcbc71720760eb5290e9eb8a1f1cc07504e111bab2f8
+size 726380
diff --git a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/DebugUtilitiesData.java b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/DebugUtilitiesData.java
index ae6e81d..9ceed8e 100644
--- a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/DebugUtilitiesData.java
+++ b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/util/DebugUtilitiesData.java
@@ -10,7 +10,7 @@
 package com.ibm.icu.dev.test.util;
 
 public class DebugUtilitiesData extends Object {
-    public static final String ICU4C_VERSION="65.1";
+    public static final String ICU4C_VERSION="66.1";
     public static final int UDebugEnumType = 0;
     public static final int UCalendarDateFields = 1;
     public static final int UCalendarMonths = 2;
diff --git a/icu4j/readme.html b/icu4j/readme.html
index 66edaa4..dda9034 100644
--- a/icu4j/readme.html
+++ b/icu4j/readme.html
@@ -14,21 +14,21 @@
 <body style="background-color: rgb(255, 255, 255);" lang="EN-US"
  link="#0000ff" vlink="#800080">
 <h1>International Components for Unicode for Java (ICU4J)</h1>
-<h2>Read Me for ICU4J 65.1</h2>
-(Last Update: 2019-Sept-16)
+<h2>Read Me for ICU4J 66.1</h2>
+(Last Update: 2019-Oct-09)
 <hr size="2" width="100%">
 
 <p>
-<b>Note:</b> This is major release of ICU4J. It contains bug fixes and adds implementations
-of inherited API and introduces new API or functionality.
-<!-- <b>Note:</b> This is a development milestone of ICU4J 65.
+<!-- <b>Note:</b> This is major release of ICU4J. It contains bug fixes and adds implementations
+of inherited API and introduces new API or functionality. -->
+<!-- <b>Note:</b> This is a development milestone of ICU4J 66.
 The contents of this document may not reflect the recent changes done
-for ICU 65 development. It is not recommended for production use. -->
-<!-- <b>Note:</b> This is a release candidate of ICU4J 65.
+for ICU 66 development. It is not recommended for production use. -->
+<b>Note:</b> This is a release candidate of ICU4J 66.
 The contents of this document may not reflect the recent changes done
-for ICU 65 development. This release candidate is intended for those
-wishing to verify ICU 65 integration before final release. It is not
-recommended for production use. -->
+for ICU 66 development. This release candidate is intended for those
+wishing to verify ICU 66 integration before final release. It is not
+recommended for production use.
 </p>
 <p>For the most recent release, see the <a
  href="http://www.icu-project.org/download/"> ICU4J
@@ -140,12 +140,12 @@
 
 <h2 class="doc"><a name="changes"></a>Changes In This Release</h2>
 
-<p>See the <a href="http://site.icu-project.org/download/65">ICU 65 download page</a>
+<p>See the <a href="http://site.icu-project.org/download/66">ICU 66 download page</a>
 about new features in this release.</p>
 <p>The list of API changes since the previous ICU4J release is available
 <a href="APIChangeReport.html">here</a>.</p>
 
-<!-- Add any ICU 65 items here. -->
+<!-- Add any ICU 66 items here. -->
 
 <h2 class="doc"><a name="license"></a>License Information</h2>
 <p>
@@ -159,11 +159,11 @@
 </p>
 <h2 class="doc"><a name="PlatformDependencies"></a>Platform Dependencies</h2>
 <p>
-The minimum Java runtime version supported by ICU4J 65 is version 7. Java runtime version 6 is not supported.
+The minimum Java runtime version supported by ICU4J 66 is version 7. Java runtime version 6 is not supported.
 </p>
 <p>
 ICU4J since version 63 depend on J2SE 7 functionality. Therefore, ICU4J only runs on
-JRE version 7 or later. ICU4J 65 is tested on JRE 7, 8, 9, 10 and 11.
+JRE version 7 or later. ICU4J 66 is tested on JRE 7, 8, 9, 10 and 11.
 </p>
 
 <h2 class="doc"><a name="download"></a>How to Download ICU4J</h2>
@@ -182,19 +182,19 @@
 &lt;dependency&gt;
     &lt;groupId&gt;com.ibm.icu&lt;/groupId&gt;
     &lt;artifactId&gt;icu4j&lt;/artifactId&gt;
-    &lt;version&gt;65.1&lt;/version&gt;
+    &lt;version&gt;66.1&lt;/version&gt;
 &lt;/dependency&gt;
 
 &lt;dependency&gt;
     &lt;groupId&gt;com.ibm.icu&lt;/groupId&gt;
     &lt;artifactId&gt;icu4j-charset&lt;/artifactId&gt;
-    &lt;version&gt;65.1&lt;/version&gt;
+    &lt;version&gt;66.1&lt;/version&gt;
 &lt;/dependency&gt;
 
 &lt;dependency&gt;
     &lt;groupId&gt;com.ibm.icu&lt;/groupId&gt;
     &lt;artifactId&gt;icu4j-localespi&lt;/artifactId&gt;
-    &lt;version&gt;65.1&lt;/version&gt;
+    &lt;version&gt;66.1&lt;/version&gt;
 &lt;/dependency&gt;
 </pre>
   </ul>
@@ -729,54 +729,54 @@
 organization
 of the data in ICU4J.</p>
 <ul>
-  <li>The primary <b>locale data</b> is under the directory <tt>icudt65b</tt>,
+  <li>The primary <b>locale data</b> is under the directory <tt>icudt66b</tt>,
   as a set of <tt>".res"</tt> files whose names are the locale identifiers. 
   Locale naming is documented the <code>com.ibm.icu.util.ULocale</code>
   class, and the use of these names in searching for resources is documented 
   in <code>com.ibm.icu.util.UResourceBundle</code>.</li>
 
-  <li>The <b>break iterator data</b> is under the directory <tt>icudt65b/brkitr</tt>,
+  <li>The <b>break iterator data</b> is under the directory <tt>icudt66b/brkitr</tt>,
   as a set of <tt>".res"</tt>, <tt>".brk"</tt> and <tt>".dict"</tt> files.</li>
 
-  <li>The <b>collation data</b> is under the directory <tt>icudt65b/coll</tt>,
+  <li>The <b>collation data</b> is under the directory <tt>icudt66b/coll</tt>,
   as a set of <tt>".res"</tt> files.</li>
 
-  <li>The <b>currency display name data</b> is under the directory <tt>icudt65b/curr</tt>,
+  <li>The <b>currency display name data</b> is under the directory <tt>icudt66b/curr</tt>,
   as a set of <tt>".res"</tt> files.</li>
 
-  <li>The <b>language display name data</b> is under the directory <tt>icudt65b/lang</tt>,
+  <li>The <b>language display name data</b> is under the directory <tt>icudt66b/lang</tt>,
   as a set of <tt>".res"</tt> files.</li>
 
   <li>The <b>rule-based number format data</b> is under the directory
-  <tt>icudt65b/rbnf</tt>, as a set of <tt>".res"</tt> files.
+  <tt>icudt66b/rbnf</tt>, as a set of <tt>".res"</tt> files.
 
-  <li>The <b>region display name data</b> is under the directory <tt>icudt65b/region</tt>,
+  <li>The <b>region display name data</b> is under the directory <tt>icudt66b/region</tt>,
   as a set of <tt>".res"</tt> files.</li>
 
   <li>The <b>rule-based transliterator data</b> is under the directory
-  <tt>icudt65b/translit</tt>, as a set of <tt>".res"</tt> files.</li>
+  <tt>icudt66b/translit</tt>, as a set of <tt>".res"</tt> files.</li>
 
-  <li>The <b>measurement unit data</b> is under the directory <tt>icudt65b/unit</tt>,
+  <li>The <b>measurement unit data</b> is under the directory <tt>icudt66b/unit</tt>,
   as a set of <tt>".res"</tt> files.</li>
 
   <li>The <b>time zone display name data</b> is under the directory
-  <tt>icudt65b/zone</tt>, as a set of <tt>".res"</tt> files.</li>
+  <tt>icudt66b/zone</tt>, as a set of <tt>".res"</tt> files.</li>
 
   <li>The <b>character property data</b> and default <b>unicode collation algorithm
-  (UCA) data</b> is found under the directory <tt>icudt65b</tt>, as a set of
+  (UCA) data</b> is found under the directory <tt>icudt66b</tt>, as a set of
   <tt>".icu"</tt> files. </li>
 
-  <li>The <b>normalization data</b> is found under the directory <tt>icudt65b</tt>,
+  <li>The <b>normalization data</b> is found under the directory <tt>icudt66b</tt>,
   as a set of <tt>".nrm"</tt> files. </li>
 
   <li>The <b>character set converter data</b> is under the directory
-  <tt>icudt65b</tt>, as a set of <tt>".cnv"</tt> files.  These files are
+  <tt>icudt66b</tt>, as a set of <tt>".cnv"</tt> files.  These files are
   currently included only in icu-charset.jar.</li>
 
   <li>The <b>time zone rule data</b> is under the directory 
-  <tt>icudt65b</tt>, as <tt>zoneinfo64.res</tt>.</li>
+  <tt>icudt66b</tt>, as <tt>zoneinfo64.res</tt>.</li>
 
-  <li>The <b>holiday data</b> is under the directory <tt>icudt65b</tt>,
+  <li>The <b>holiday data</b> is under the directory <tt>icudt66b</tt>,
   as a set of <tt>".class"</tt> files, named <tt>"HolidayBundle_"</tt>
   followed by the locale ID.</li>
 
@@ -875,7 +875,7 @@
 <I> Note: This procedure assumes that all 3 sources are present</I>
 <ol>
     <li>Checkout or download CLDR version 'release-36'</li>
-    <li>Checkout ICU with tag 'release-65-1'</li>
+    <li>Checkout ICU with tag 'release-66-1'</li>
     <li>cd to icu4c/source/data directory</li>
     <li>Follow the instructions in icu4c/source/data/cldr-icu-readme.txt</li>
     <li>Rebuild ICU4C with the newly generated data.</li>