Chicago itself is on a well-arranged grid system, and its south and west suburbs generally follow the same grid (so addresses on a street in one town might proc

Chicago itself is on a well-arranged grid system, and its south and west suburbs generally follow the same grid (so addresses on a street in one town might proceed from 9200 S to 10400 S, for instance, and the next town picks up at 10400) and thus it's not super important to know exactly which town you're in. But then there's the north and northwest suburbs... In most (all?) of the suburbs out in that direction, the overall roads are laid out on exactly same grid as Chicago, but they are numbered with a separate zero location in each town, which in general are not coordinated in any way. So it is vitally important when navigating to know what town you're in and what you're aiming for; and for extra degree of difficulty, many town boundaries run down the middle of the major grid streets, so you can be headed north and addresses on your right will be increasing North addresses from one town and decreasing South addresses from another. And of course the town boundaries are often not well-marked....