A controversial measure that would change how the U.S. Census counts Illinois prison inmates is advancing in Springfield.

The census counts Illinois’ prison inmates as residents of the town the prison is in, not the town they came from.

That population can affect a region’s eligibility for government money.

State House members narrowly approved a bill Wednesday saying the state will start keeping track of an inmates’ last known address for census purposes.The measure passed with the bare minimum of favorable votes, 60-55.

The bill’s passage upset Republican State Rep. Chad Hays from Danville, which has a prison that currently holds about 1,800 inmates, according to the Illinois Department of Corrections.

“I just lost 2,000 residents,” Hays said after the vote.

He sarcastically said he’ll start sending expenses to the City of Chicago for projects paid for with government money.

But State Rep. Monique Davis of Chicago suggested those who have prisons in their districts have a financial interest in keeping their prisons full.

“Let’s see how many enhanced penalty bills will pass, let’s see how many new bills were put in the criminal code if that population is no longer valuable to certain groups,” she said.

The measure still needs the support of the Senate.

Tony Arnold covers Illinois politics for WBEZ. Follow him @tonyjarnold.