There seems to be two different units being used. Supposedly the border zone is 100 "air miles" which is later implied to be a factor 1.14 larger than regular m

There seems to be two different units being used. Supposedly the border zone is 100 "air miles" which is later implied to be a factor 1.14 larger than regular miles. So the 100 air miles mean 114 miles, and those extra 12 nautical miles ends up not mattering for both west and east coasts. You are right about Chicago though.