Cook county's population is about half Chicago and half suburban townships. Growth since 2010 is only about 0.35%/year according to census estimates and is fairly evenly divided between city and townships, and no township stands out for high growth since it's all mostly built up. Thus, the 2010 precinct results are a fairly good place to start a forecast for 2014.
The Cook County Clerk put out a detailed
report after the 2010 general election, and the maps of precinct results show the relative party strengths in the county. Here are the maps from both the Gov's race as well as Kirk's win for US Senate. The comparison between the two gives a sense of the difference between a narrow loss and narrow win for the Pub in a statewide race.
