The city of Chicago lost nearly seven percent of its population over the past decade, according to U.S. Census data released Tuesday.

Chicago had close to 2.9 million residents in 2000. According to the 2010 census, there are now 200,000 fewer Chicagoans.

“The population of Chicago dropped considerably more than was expected given the estimates during the decade from 2000 to 2009, so that was something of a surprise,” said Ken Johnson, a demographer at the University of New Hampshire who used to work at Loyola University Chicago.

“The other interesting piece of data for Chicago is going to be that the black population of Chicago dropped quite significantly,” Johnson said.

That represents the bulk of the city’s net population loss.

All this data will be key as lawmakers redraw legislative boundaries this year, especially given that Illinois will lose a seat in the U.S. House.

The numbers released Tuesday also show that the population of suburban Cook County mostly held steady, while some other counties in the area saw big booms.

“Kendall County’s population doubled,” Johnson noted. “Will County went up by 175,000.”

Johnson suggested those increases would probably have been even higher if not for the recession slowing growth at the end of the decade.