Parishes, boroughs and planning regions

Louisiana parishes

The Census Bureau's glossary states that the primary legal divisions of most states are counties and that in Louisiana they are parishes. A parish works like a county in Census tables and has a 5 digit code starting with 22. Louisiana's 64 parishes have a median of 31,591 residents and 646 square miles of land. East Baton Rouge Parish is the most populous and Vernon Parish the largest by land. See all Louisiana parishes.

Alaska boroughs and census areas

Per the glossary, Alaska's county-equivalents are organized boroughs, city and boroughs, municipalities, and census areas. Census areas are delineated for statistical purposes by the State of Alaska and the Census Bureau together.

Alaska has 30 of these units with 571,242 square miles of land, 16.2% of all US land in this data. That makes them the largest county-equivalents by far: the median Alaska unit covers 7,481 square miles, and Yukon-Koyukuk covers 145,769. The list changes more than most. Valdez-Cordova split into Chugach and Copper River in 2019.

Connecticut planning regions

The Census glossary notes that Connecticut's counties were dissolved as functioning governments, but Census data kept using the eight historical counties as county-equivalents. In 2022 the Census Bureau finalized the state's nine councils of governments as the county-equivalent unit. They appear in data as planning regions with codes 09110 to 09190.

The switch breaks time series. A Connecticut county table from 2020 and one from 2024 have different units and codes, and the boundaries do not nest. The maps on this site use the Census 2024 cartographic boundary file, which draws the 9 regions. The largest region by population is Capitol Planning Region, with 991,508 residents.

The District of Columbia

The glossary notes that DC has no primary divisions and is treated as one equivalent entity. It appears in county tables as a single row, code 11001, with 702,250 residents on 61.1 square miles of land.

The four side by side

Working with these units in data

• Louisiana parishes need no special handling. Join on the 5 digit code and label them parishes.
• Alaska's units have changed in recent years. Check the vintage of both files before joining, and expect 02261 in older data and 02063 and 02066 in newer data.
• Connecticut needs a crosswalk for any time series that spans 2022. The Census Bureau publishes one with its county change notes.
• DC appears in both state and county tables. Count it once when summing counties to a national total.

How their size compares

Against the national median county of 616 square miles, the median Alaska unit is 12 times larger, while the median Louisiana parish is 1.05 times the national median, and the median Connecticut planning region is 0.86 times it. In residents, Connecticut's regions are large units, with a median of 335,666 against 26,122 nationally.

How they appear on maps

On county maps, Louisiana parishes and Alaska units draw like any other county. Connecticut's 9 planning regions draw from the Census 2024 cartographic boundary file, the same vintage as the population tables, so the outlines and the figures describe the same units.

The same file carries Alaska's 30 boroughs and census areas, including Chugach (02063) and Copper River (02066), the two census areas that replaced Valdez-Cordova in 2019. A map that still shows Valdez-Cordova, or Connecticut's 8 old counties, was drawn from an older boundary file and will not join cleanly to current population tables by FIPS code.