What to Make of the 2020 Apportionment Counts?

We recently recommended a new online tool from the Census Bureau to help stakeholders work with 2020 Census apportionment data once it is released this month.

The “Historical Apportionment Data Map” displays apportionment results for each census. While it currently just includes 1910 to 2010, the Bureau has said that the 2020 apportionment data will be added to the map as soon as they become public.

It is important to be reminded that the state apportionment counts differ significantly from the final 2020 state population totals that will come later, as well as the annual Population Estimates for each state. The apportionment calculation is based upon the total resident population (citizens and noncitizens) of the 50 states. In 2020 the apportionment population also includes U.S. Armed Forces personnel and federal civilian employees stationed outside the United States and their dependents living with them that can be allocated back to a home state. The population of the District of Columbia is not included. More can be found here.

The most recent population estimates are a rough tool used by experts to project the apportionment such as here and also here. While generally close to the official apportionment release, readers are cautioned that small differences can affect which state gets the 435th seat in the House of Representatives.

Quality of the Counts

For the first time ever, the Census Bureau will also release some process indicators that will be our first hint of how well the 2020 count went. These indicators will not tell us about important metrics on the overall quality or completeness of the count, (such as the net undercount or the differential undercount across race subgroups), but they will begin to tell the story of how well the Bureau adapted to disruptions in operations cause by the Covid-19 pandemic. Look for the Bureau to report on state level indicators such as:

  • The percent addresses determined to be occupied, vacant, or non-existent.
  • How Census determined household status. That is through self-response, in person interview, Group Quarters or unresolved.
  • For other than self-response, the  percentage of occupied addresses resolved by interview, proxy, or administrative records.
  • The percent of deleted addresses later resolved with a proxy interview or by administrative records.

On Wednesday, April 21, 2021 at 1 p.m. EDT, the Census Bureau will host an Educational Webinar on these metrics.  Where possible the Bureau will compare to 2010 metrics of the same kind. Beginning in May, the Bureau will begin progressively releasing other quality metrics, including an independent analysis by a outside team led by experts from the American Statistical Association.