DIVIDING ILLINOIS: What would happen if Cook County were to become a state by itself?

AUTHOR’S NOTE: This blog post is the second in a three-part special series of blog posts, entitled “Dividing Illinois”, about three different proposals to split Illinois into two states, none of which are supported by the author. You can view the previous blog post in the series here.


A few days ago, I wrote about a legislative proposal (Illinois HB101), supported by several far-right Republican state legislators, that would essentially expel the City of Chicago from the State of Illinois and ask Congress to grant Chicago statehood. As I wrote, the legislation, which has virtually zero chance of passing in the Democratic-controlled Illinois General Assembly, could actually result in two Democratic-leaning states being created, despite the bill’s backers being some of the most conservative Republicans in the General Assembly who drafted the legislative proposal with the apparent attempt of making Illinois a Republican-leaning state.

However, it would not be that hard for Republicans, assuming they got control of the U.S. presidency, the Illinois governorship, both houses of the U.S. Congress, and both houses of the Illinois General Assembly at the same time (something Republicans have never done in my lifetime, Republicans held all of those except the U.S. Presidency from 1995-1997), to create what, at least in the next few decades, would be a clearly Republican-leaning state. In fact, they could do so by expelling Cook County, the state’s most populous and most Democratic-leaning county, from the State of Illinois and asking Congress to grant Cook County statehood. For the purposes of this blog post, I’m going to refer to all parts of the State of Illinois outside of Cook County as Greater Downstate Illinois.

To give you a general idea of what the political ramifications of making Cook County a state by itself, here are two tables (sourced from this spreadsheet that I created using Illinois State Board of Elections, Chicago Board of Election Commissioners, and Cook County Clerk’s office data), the first of which is of the 2018 gubernatorial election in Illinois, and the second of which is of the 2016 U.S. presidential election in Illinois, showing Cook County percentages and Greater Downstate Illinois percentages for every candidate who received at least 0.1% of the statewide vote:

PritzkerRaunerJacksonMcCann
DemRepLibCon
Cook County71.87%24.26%2.01%1.86%
Greater Downstate Illinois43.62%48.00%2.66%5.73%
ClintonTrumpJohnsonSteinMcMullin
DemRepLibGrnInd (W/I)
Cook County74.68%21.00%2.72%1.51%0.09%
Greater Downstate Illinois43.80%50.13%4.47%1.31%0.29%

As you can tell, Cook County, if it were a state by itself, would be one of the most Democratic states in the entire country, if not the most Democratic state in the entire country. On the other hand, Greater Downstate Illinois, which would presumably retain the Illinois name, date of statehood, and Class 2 and Class 3 Senate seats, would be a clearly Republican-leaning state, and, while Republicans would not be complete locks to win every statewide race in an Illinois without Cook County, the Republicans would clearly be the natural governing party of an Illinois without Cook County.

Splitting Cook County and Greater Downstate Illinois into two separate states would have the following political ramifications:

  • In terms of the Electoral College, Donald Trump would have received 13 more electoral votes, and Hillary Clinton would have received 11 fewer electoral votes, than the real-life 2016 result, and Republicans would have a easier path to an Electoral College majority.
  • In terms of the U.S. Senate, Cook County would likely send two Democrats to the U.S. Senate, Greater Downstate Illinois would likely send two Republicans to the U.S. Senate, resulting in a net gain of two seats for the Republicans and expanding the Senate majority from 53-47 to 55-47.
  • In terms of the U.S. House, Republicans would be in position to gerrymander Greater Downstate Illinois’s 11 congressional districts to their benefit, more than cancelling out any advantage that Democrats would be expected to get out of a seven-member, expected all-Democratic U.S. House delegation from Cook County.
  • In terms of state legislatures, Cook County would likely have a predominantly Democratic state legislature, while Greater Downstate Illinois would likely have a Republican-controlled state legislature.

It’s very obvious why Democrats who control Illinois’s state government would not support separating Cook County from the rest of the state (in fact, I don’t support such an idea), since doing so would give Republicans a significant political advantage. However, I could imagine why some Republicans would be very reluctant to support separating all of Cook County from the rest of the state. Keep in mind that downstate Illinois benefits financially from tax revenue generated in the wealthier areas of the Chicago metro area, including the wealthier areas of Cook County, and that revenue stream would be lost if Cook County were to be granted statehood as a separate state from the rest of Illinois.

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