Technically, over 30 miles from the Chicago shore, but only a few hundred feet from the beach at the Indiana Dunes National Lakeshore. On clear days, the Chicago skyline can be seen from the "dunes" beaches, making the distance across Lake Michigan seem short, but at this point, it's almost 40 miles across. The curvature of the earth prevents the bottom of the buildings from being seen so far away. In fact, an average person standing on the beach can only see about 3 miles - that's where the curvature of the earth begins to slope away from them, and the horizon is perceived. Elevated on a hill or dune, and the distance is increased; add a 110 story building on the horizon, and one can easily see it from 37 miles away.
Posted by Tom Gill at Sunday, August 11, 2013