Connecticut changes from Counties to Planning Regions

1960: Counties Abolished in Connecticut

In most states, counties are the primary governing entity below the state government. Their primary responsibilities often include recordkeeping, election administration, road construction and maintenance, parks management, and law and code enforcement. Most commonly, counties are governed by an elected board of supervisors or county commission that performs both legislative and executive functions. Many have other elected or appointed county positions (i.e., “row offices”), including assessors, auditors, attorneys, clerks, and tax collectors. They also act as convenient geographical regions to use for statistical purposes.

On October 1, 1960, Connecticut officially abolished counties as a system of independent government and administrative entities. The duties and functions of the state's eight counties were eliminated by legislation passed in 1959 and 1961. Prior to their elimination, county governments had limited functions. The 8 counties in Connecticut that most are familiar with (Fairfield, Hartford, Litchfield, Middlsex, New Haven, New London, Tolland, and Windham) have existed only as geographical regions since 1960. Lousiana has also done this with Parishes and Alaska with Boroughs.

2022: U.S. Census approves Petition

In 2022, the U.S. Census Bureau approved Connecticuts request to adopt its nine planning regions as county-equivalents (a petition started in August 2019). These nine planning regions replace Connecticut's eight counties used historically. They were designed to work with local geography and population to better serve as administrative boundaries. Growth in Connecticut had no regard for the original counties abolished in 1960, so a new method of division was required. This would enable a more meaningful geographic area for statistical analysis and decision making at the sub-state level. The 8 counties were replaced with 9 Councils of Government (COGs), also known as Planning Regions. The new Planning Regions were accepted with new names and FIPS Codes (below). The U.S. Census began publishing Core Based Statistical Areas (CBSAs) at the Planning Region summary level in July 2023 with the Office of Management and Budget (OMB) update.

2024: Planning Regions go into effect

Connecticut's nine planning regions became effective as county-equivalents on July 1, 2024. This is a permanent change. The transition from data sources using counties to the new planning regions has been, and will continue to be, ongoing. The U.S. Census began releasing data at the new region level in 2023. The USPS updated its data products to use planning regions in July 2024. ZIP-Codes.com now provides the Planning Regions for each ZIP Code, but has prepared crosswalk files for those who continue to need the historical county assignment at the ZIP Code and ZIP+4 level. Also provided is a Town to COunty Crosswalk file.

Below are several maps prepared that can be used to see the relation of Towns, Historical Counties, Planning Regions, and even ZIP Codes.

Maps

Connecticut Historical County and Town Boundary Map

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Connecticut Planning Region and Town Boundary Map

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Sources and Official Announcements

• OLR Research Report: COUNTY GOVERNMENT IN CONNECTICUT
• U.S. Federal Register: Change to County-Equivalents in the State of Connecticut
• U.S. Bureau of Labor Statistics: New 2024 Connecticut Counties
• State of Connecticut: Office of Policy and Management: Planning Regions and Regional Councils of Governments
• OPM Press Release: CT Planning Regions Proposed to Become County Equivalents
• CT Data Collaborative: Geographic Resources for Connecticut's new "County-Equivalent" Planning Regions
• StoryMap: CT Planning Regions Approved to Become County Equivalents
• CTInsider: Connecticut Census data no longer recognizes counties as regional planning organizations are strengthened

ZIP Code to County Crosswalk

The USPS reports a county for each ZIP Code. In July 2024, the USPS data products were updated to report the new Planning Region for each ZIP Code in place of the historical county. For many systems that rely on County information, this is a challenge. The old counties are no longer available from the Postal Service, only the new Planning Regions. Customers needing to connect ZIP Codes to Counties must add support for this exclusively for CT ZIP Codes.

The ZIP Code to County Crosswalk file for Connecticut shows the current active ZIP Codes in the state of CT. For each one, the City name and classification of the ZIP Code is shown. For the historical counties in CT, the primary County FIPS and County Name are provided as well as the new primary Planning Region FIPS and Name as assigned by the USPS.

Download Connecticut ZIP Code to County Crosswalk CSV File

ZIP+4 to County Crosswalk

The USPS reports a county for each ZIP+4 record. In July 2024, the USPS data products were updated to report the new Planning Region for each ZIP+4 in place of the historical county. For many systems that rely on County information, this is a challenge. The old counties are no longer available from the Postal Service, only the new Planning Regions. Customers needing to connect ZIP+4 records to Counties must add support for this exclusively for CT ZIP Codes.

The ZIP+4 to County Crosswalk file for Connecticut shows the current active ZIP+4 records in the state of CT. Each record in this file includes the USPS supplied Update Key, ZIP Code, ZIP+4 Low Number, ZIP+4 High Number, Region FIPS, Region Name, Historical County FIPS, and Historical County Name. You can marry this information to the ZIP+4 data by using either the UpdateKey or ZIP Code and ZIP+4.

Download Connecticut ZIP+4 to County Crosswalk CSV File

Town to County Crosswalk

The U.S. Census Bureau adopted Connecticut's nine planning regions as county equivalents-- new county-level geographies for Connecticut for statistical purposes, replacing Connecticut's eight counties in Census Bureau data products. The county equivalents have new FIPS codes.

The U.S. Census Bureau data and publications have transitions to using the county equivalents instead of counties in 2023. To help ease this transition, this crosswalk includes town FIPS codes for both the original counties and the new county equivalent Planning regions. Towns therefore have two FIPS identifiers. The town boundaries did not change.

TownFIPS2020 include the FIPS code from its county.

TownFIPS2022 include the FIPS code from its county equivalent/planning region.

Download Connecticut Town to County Crosswalk CSV File

Resources for Connecticut Historical Counties

ZIP Code to County Crosswalk File: A Connecticut ZIP Code to County Crosswalk lists all current ZIP Codes from the U.S. Postal Service in CT as well as their primary Planning Region and Historical County assignments. These are actual ZIP Codes and not Census ZCTAS. This information is updated monthly to always provide the current active ZIP Codes. Fields include: ZIP Code, City, Classification, County FIPS, County name, Planning Region FIPS, Planning Region Name. Updated: March 1, 2025

ZIP+4 Code to County Crosswalk File: A Connecticut ZIP+4 to County Crosswalk lists all current ZIP+4 records from the U.S. Postal Service in CT as well as their primary Planning Region and Historical County assignments. This information is updated monthly to always provide the current active ZIP+4's. Fields include: Update Key, ZIP Code, ZIP4 Low, ZIP4 High, Region FIPS, Region Name, County FIPS, County Name. Updated: March 1, 2025

Town to County Crosswalk: The Town to County Crosswalk shows each Town in Connecticut along with it's 2020 FIPS, 2022 FIPS, Planning Region, and historical County assignment. Fields include: Town, TownFIPS2020, TownFIPS2022, PlanningRegionFIPS, PlanningRegionName, CountyFIPS, CountyName. Updated: January 21, 2025

CT County & Planning Region Boundaries Shapefile: A shape file containing the boundaries of historical Counties and Planning Regions for Connecticut together in one file can be downloaded here. Fields Included: geom, ID, StateAbbrev, StateFIPS, CountyFIPS, Name, NameLSAD, StateCountyFIPS, and LSAD. The download contains a SHP file, KML, WKT, and other popular formats.

County Shape Files: The U.S. Census provides a national county and county-equivalent shapefile which can be downloaded here. This does not include historical CT Counties. It has all U.S. counties, LA Parishes, AK Boroughs, and CT Planning Regions.

CT Planning Region Boundary Data: From the CT Geodata Portal, the CT Planning Regions includes individual polygons representing each of the 9 Planning Regions that make up the state of Connecticut.

CT Counties Boundary Data: From the CT Geodata Portal, the Connecticut Counties includes individual polygons representing each of the 8 historical counties that make up the state of Connecticut.

CT Municipalities (with FIPS) Boundary Data: From the CT Geodata Portal, the CT Municipalities (with FIPS) includes individual polygons representing each of the 169 Municipalities that make up the state of Connecticut.