What is a decennial census?

Decennial Census 2020 Data

Apportionment & Redistricting


What is a Decennial Census?

The Census is an invaluable resource for understanding the current state of population and housing in the United States. As required by the Constitution, the Census Bureau undertakes a full count of the population once every ten years (decennially), during year that start a new decade (e.g. 1990, 2000, 2010, 2020, etc). The product of that count is typically released incrementally over the years following the count, and influences everything from how we vote in elections, to how the federal, state, and local governments allocate funding.

Decennial Census 2020 Data

The US Census released a subset of Decennial Census 2020 data August 12, 2021 for the purpose of redistricting. The tables included are:

  • P1: Race

  • P2: Hispanic or Latino, and Not Hispanic or Latino by Race

  • P3: Race for Population 18 Years and Over

  • P4: Hispanic or Latino, and Not Hispanic or Latino by Race for the Population 18 Years and Over

  • P5: Group Quarters Population by Major Group Quarters Type

  • H1: Occupancy Status

The redistricting data subset is available in mySidewalk.

The full set of data from the Decennial Census 2020 has not yet been released.

Upcoming Decennial Census 2020 Data Releases

As of December 2022, the upcoming data release dates announced by the US Census Bureau are as follows:

  • May 2023: Demographic Profile and the Demographic and Housing Characteristics File (DHC)

  • Detailed Demographic and Housing Characteristics File (Detailed DHC)

    • This will be split into 3 different products

    • August 2023: Detailed DHC-A

      • will include population counts, sex, and age statistics for detailed race and ethnic groups

    • TBD: Detailed DHC-B

      • will include household type, tenure (renter vs owner)

    • TBD: Detailed DHC-C

      • will include complex household and people characteristics

Apportionment & Redistricting

A core function of the Decennial Census is determining how many representatives each state sends to Congress. The first batch of Census data released by the US Census Bureau involves very basic information to fulfill this duty.

States undertake the process of redistricting, which is the redrawing of the US Congressional boundaries using the the released 2020 Decennial Census data. In addition, states also often redraw their state house and state senate districts. Individual cities also use the the data to update their city council districts or wards.

What does this mean for mySidewalk customers?

Redistricting (also called apportionment) data enjoys a high level of media coverage and visibility, because it is the first data released from a Decennial Census, and because of its impact on our federal representation.

There is a lag of several years between when the new set of US Congressional districts, state senate, and state house districts are redrawn and when data sources such as the US Census, HUD, CDC, USDA, EPA, BLS, and others generate data values for these new geographies.

The geographies currently used in mySidewalk are the vintage that matches the most recent ACS 5-year estimates. You can check out this table of mySidewalk geography vintage at the bottom of our help article that explains each geography level offered in mySidewalk products.


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