The east-west part of Chicago’s Dwight D. Eisenhower Expressway, aka “the Ike” or I-290, which turns into Congress Parkway in downtown, is about one mile north of the Monona/Harrison-to-Linn/Johnson county line. (About 41°51’N.) In fact, if you add five to longitude numbers in downtown Chicago, you will find yourself in southern Tama County along County Road E69.
Much of the Chicago metro area is in the latitudes between US 20 and I-80 in Iowa; US 20 dips southeast starting at Rockford to go into the city.
This isn’t particularly ground-breaking, but I was playing around with some numbers after I took the Jeopardy online test.
Meanwhile, this weekend Google is offering “8-bit mode” for “quests” like on on Nintendo games. These two characters are hiding north of the Chicago Loop.