New Census Estimates Project Congressional Apportionment

Daniel McGlone
Published in
3 min readDec 31, 2019


The U.S. Census Bureau just released its national and state population estimates for 2019, which show the nation’s population growth has slowed this decade. Using the population estimate for each state, we can project which states will gain and lose seats in Congress during apportionment in 2020.

The map below shows the current apportionment based on the 2010 Census.

Current U.S. House of Representatives Apportionment

What is apportionment?

Congressional apportionment is a process outlined in the constitution that guides how many representatives each state gets in the U.S. House of Representatives. Every ten years, the decennial Census produces the official population for each state and that data is used to reapportion all 435 Congressional seats. Because each of the 50 states is guaranteed one seat no matter how small its population, a formula must be used to apportion the remaining 385 seats. Since the early 20th Century, the U.S. has used the Equal Proportions Method to calculate the number of seats each state will get.

Trends in apportionment for 2020

While we don’t have the official 2020 Census results yet, we can apply the Equal Proportions Method to the 2019 estimates to project which states will gain or lose seats. Below, see a map of which states are projected to gain or lose seats based on the latest Census estimates.

Texas, which has gained over 4 million people since 2010, is the only state likely to pick up two seats. Other states that will gain seats are Arizona, Colorado, Florida, North Carolina, and Oregon. Montana will also gain a seat — going from 1 to 2 — which means they will have to district for the first time since the 1980s.

Many northeastern and Midwest states are projected to lose one seat. The most populous state in the U.S., California, will lose one seat due to slowing population growth.

What it might mean for politics

While traditionally Democratic states like California, New York, and Illinois are losing seats and Republican states like Texas and Florida are gaining seats, that doesn’t necessarily mean it helps Republicans. Intrastate population changes will determine how and where the districts will end up being drawn. In Texas, most of the population growth has been in the Democratic-leaning cities, while much of the Republican-leaning rural areas of the state have lost population. Of course, gerrymandering can disrupt this process which means predicting how this turns out for any political party is difficult at this time.

It’s important to note that these are just estimates — and in fact, the Census Bureau has revised previous estimates downward to note a slowdown in international immigration towards the end of the decade. Furthermore, some states are spending a lot of money to make sure a full and accurate count is done, while some states are not spending any money at all. The slowdown in international migration and lack of spending on Census outreach efforts could come back to bite Republicans in Florida, for example, which is close to gaining two seats instead of one.

The Census is critical for determining not just apportionment — but how districts are drawn. On the Cicero team, we track redistricting as it occurs and update our data as soon as new districts are available.

We’ll be tracking the process of apportionment and redistricting in 2020 and beyond. Check out what district you are in now and any future districts with our Elected Officials and Districts tool.



Daniel McGlone
Editor for

Senior GIS Analyst at Azavea and Data Manager for Cicero