Trump ordered a new census that doesn’t count undocumented immigrants. Will it really happen — and what would be the impact?

President Trump said Thursday that he is ordering his administration to begin work on a new census that excludes undocumented immigrants from the national tally of people living in the United States.

“People who are in our Country illegally WILL NOT BE COUNTED IN THE CENSUS,” he wrote in a post on Truth Social.

It’s unclear from his post whether Trump intends to have the change in place for the next official census, which won’t be conducted until 2030, or a different count completed sooner.

Leaving undocumented immigrants out of the census would run directly against language in the Constitution that orders the government to count “the whole number of persons in each State.” The Constitution also gives Congress, not the president, control of the census.

During his first term, Trump attempted to have a question added to the census that asked respondents about their citizenship status. After a long legal battle, the Supreme Court ultimately blocked the move. Researchers have found that a citizenship question would likely lead to an inaccurate record of the U.S. population, with Latinos especially being undercounted.

The Supreme Court has not formally ruled on whether undocumented immigrants can be left out of the census entirely. The justices were given an opportunity to weigh in on that question in the final months of Trump’s first term, but chose not to.

Why does the census matter?

Census data is crucially important. It is by far the most accurate and comprehensive way we have to know how many people live in the U.S., what their backgrounds are and what their lives look like.

It also plays a big role in who controls Congress. Census numbers are used to decide how many members each state gets in the House of Representatives. Every 10 years, certain states gain extra seats in Congress while others lose them after the census provides an updated view of population flows across the country. The census affects presidential elections as well, because each state’s Electoral College votes are based on the size of its congressional delegation.

The census also helps Congress decide where trillions of dollars in federal spending go every year. The distribution of federal funding for education, transportation, law enforcement, public health and much more is all informed by the population figures that the census provides.

What would it mean if undocumented people weren’t included?

There are an estimated 11 million people living in the U.S. illegally, according to the Department of Homeland Security. Leaving them out of the census would lower the total U.S. population by about 3%.

The impact would be especially pronounced in the states that have the most undocumented residents. California has by far the largest undocumented population, 2.6 million people as of 2022, according to DHS data. Next is Texas with 2 million, followed by Florida (590,000), New Jersey (490,000) and Illinois (420,000).

The House of Representatives has one member for roughly every 760,000 people in the U.S., based on 2020 population figures. Removing undocumented people from the census could be enough on its own to shift multiple House seats out of California and Texas to other states. It would also lower the number of Electoral College votes in those states, which could make a huge difference in an extremely tight presidential race in the future.

States and cities with a lot of undocumented immigrants would likely receive less funding from the federal government because official tallies of their populations wouldn’t include all of the people who actually live there.

What happens next?

So far, there has been no follow-up from the Trump administration on how it might carry out the president’s call for a new census. Any formal effort to alter the census or complete one outside of the normal 10-year cycle would almost certainly be challenged in court.

Rep. Marjorie Taylor Greene, one of Trump’s staunchest allies in the House, introduced a bill last month that would go even further than the president’s order. Her Making American Elections Great Again Act would lead to a new census that only counts American citizens and reapportion House seats based on those new numbers. The prospects of that bill making it through Congress appear to be slim, and it would inevitably face constitutional challenges if it did somehow pass.

Trump’s census call comes in the midst of a heated partisan fight over redistricting, prompted by Texas Republicans’ move to redraw the state’s congressional lines outside of the typical cycle to secure the GOP as many as five additional seats in the House in next year’s midterms. Blue state Democrats have pledged to carry out their own redistricting if Texas installs its proposed new maps. GOP leadership has reportedly been pressuring Republicans elsewhere in the country to follow Texas’s lead.