HARRISBURG, Ill. (AP) — A congressional district in southern Illinois is expected to disappear following the 2020 census, raising concerns from about the redistricting process that determines the number of seats a state gets in Congress.

The 15th Congressional District, which stretches across nearly 15,000 square miles of southern and central Illinois, will most likely be eliminated after the 2020 census because its population has been steadily dwindling, according to experts.

U.S. Census Bureau data shows that from 2013 to 2018, the district’s population dropped by about 14,000, to 690,000– jeopardizing a seat in the U.S. House of Representatives because a congressional district must have roughly 710,000 residents.

Population drops allow lawmakers, particularly those in the majority party of a state, to redraw congressional district maps in a process called redistricting. In Illinois, Democrats dominate both the General Assembly and the governor’s office, empowering them to map the entire state’s congressional districts. Map drawing is slated to begin next year.

The redistricting calculus means that while a Republican candidate is expected to take the conservative district in November, the winner will likely serve just one term, the Belleville News-Democrat reported.

U.S. Rep. John Shimkus who currently represents the 15th District already declined to run for reelection after more than 20 years in Congress.

If the 15th District is eliminated, Democrats can draw a map that makes one of the other Republican southern districts, the 12th or the 13th, more competitive in elections, according to John Jackson, a visiting professor at the Paul Simon Public Policy Institute.

While U.S. Rep. Mike Bost, R-Murphysboro, has a firm hold on the 12th District, which covers most of deep southern Illinois, Republican U.S. Rep. Rodney Davis from Taylorville faces a close race in November.

State Senate Minority Leader Bill Brady, a Republican from Bloomington, said he hopes Democratic Gov. J.B. Pritzker will support a joint resolution amendment that would change the Illinois constitution’s provisions on redistricting. The measure, which attracted broad bipartisan support, would make the mapping process fairer, Brady argued.

“The only way the governor can live up to his commitment and perception as well as reality is to help us push for fair maps,” Brady said.

Cities throughout Illinois are pushing for an accurate census count. Officials estimate they’ll lose $1,400 per person not counted in the 2020 census.

Census invitations will begin going out to homes across the country between March 12 and March 20. If people don’t respond by the end of April, census takers will follow up in person between May and July.

The U.S. Census Bureau is accepting applications for hundreds of thousands of temporary jobs this year to help with the 2020 Census count. Governor Pritzker is putting roughly $20 million into Census outreach across the state as well.