Illinois's loss of population is crippling, Bruce Rauner emphasized in his State of the State address. And the decline is considerable—so much so that the state could lose a House seat, according to analysis by Election Data Services, a political consulting firm.

But where is the exodus actually coming from? The Census Bureau doesn't have county-by-county figures for 2015, but it does have the change from 2010 to 2014. And it looks like this, with green representing degrees of growth, red decline:

Cook County and the collar counties are growing; Cook County grew by over 50,000 people. The main reason is births: 300,000 over five years, compared to about 170,000 deaths. (Not all counties have a net natural increase; in LaSalle County, there were more deaths than births over the same period.) Meanwhile, 152,000 people left Cook County, offset by only 77,000 moving into it.

The big loser? Rockford’s Winnebago County, which lost about 6,700 people. Rockford alone accounted for almost 4,000 losses; as the Rockford Register-Star reported, it was the fifth-largest loss among U.S. cities.

A few counties outside of the Chicago area grew slightly over the past few years, but virtually every county had a net loss from domestic migration. (Downstate Williamson County saw the largest gain from domestic migration, through which it added a mere 415 people). To the extent that counties did grow, it was through foreign immigration and births.

And there's something of a theme among the counties that had four-figure growth: They're either close to Chicago or they have college towns.

Champaign County, home to the University of Illinois, for instance, added about 6,000 people in that five-year period. McLean County, home of Illinois State University, added almost 4,500, as did Sangamon County, home of the University of Illinois-Springfield. Jackson County, where Southern Illinois University is located, lost population, but some of that is because many people commute from neighboring Williamson County, according to this state report shows.

Which shouldn't be a surprise. As the U.S. Department of Agriculture stated in its 2014 report "Rural America at a Glance":

Across the rural-urban continuum, recovery from the recession has generally been more successful in counties where the working-age population has relatively high education levels. Nonmetro counties in the top quarter ranked by college completion in 2007-2011 tended to gain population in 2010-2013, while lower ranked counties tended to lose population. One likely reason is that the occupations and industries associated with higher education, such as education and health services, have done relatively well since the recession, providing high-education counties with more jobs to support a growing population.

Meanwhile, Illinois continues to stumble on without a budget for its state university system. If the governor and legislature are, as Rauner's State of the State speech suggests, focusing on the state's population loss, they'll have to pay attention to where it is growing, and why.