How are people “voting with their feet” between Cook County and NW Indiana?

Residents on one side are four times more likely to move— but it might not be the one you think

Pierogi Fest in Whiting, Indiana. Connie / flickr

It’s a common refrain: Illinois is losing residents to neighboring states because of its undesirable policies, especially tax policy. Because of its proximity to famously low-tax Indiana, the Chicago region is particularly vulnerable: a resident of Cook County could easily jump across the border and enjoy a lower tax bill without giving up access to jobs and amenities in Chicago.

So is that what’s happening? Are residents of northeast Illinois “voting with their feet” by stampeding to northwest Indiana?

At first glance, Census statistics seem to indicate that the answer is yes. The most recent numbers suggest that between 2010 and 2014, an average of 9,400 residents of Cook County moved to Lake and Porter counties in Indiana each year— and just 4,700 residents of Lake and Porter counties moved into Cook.

In this map, counties highlighted in red are in the Chicago metropolitan area. The two highlighted counties in Indiana are Lake and Porter. Wikimedia Commons

But before we say that Cook County residents have revealed their preference for Indiana-style policies by voting with their feet, there’s something else to consider: base population. Cook County may send more people to northwest Indiana than vice-versa, but it also has more people to begin with: Over 5.2 million, as compared to about 650,000 in Lake and Porter counties.

It turns out that when you adjust for population, things look very different. Out of every 10,000 Cook County residents, about 18 move to Lake or Porter counties in Indiana each year. Meanwhile, for every 10,000 residents of Lake or Porter counties, about 71 move to Cook.

In other words, a random resident of northwest Indiana is four times more likely to move to Cook County than someone from Cook is to move to northwest Indiana. While it doesn’t change the fact that Cook County has a migration deficit, it does show that that deficit is driven almost entirely by Cook’s much greater size — not because Cook residents are especially likely to move to northwest Indiana.

In fact, between 2010 and 2014, residents of Cook County were more than 20 percent more likely to move to far-off, high-tax California than next-door, low-tax northwest Indiana.

Illinois does indeed have a migration problem, and a deeply broken state government whose failures to pass a budget, address a long-term structural deficit, and properly fund public services like healthcare and education have hurt countless residents across the state. But this analysis shows that using raw migration statistics to tell just-so stories about what Illinois residents are “voting” for is a tricky, and sometimes misleading, exercise.

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