Grid Unlocked

The forefathers of Chicago had the sense to layout the city in a logical grid which makes it relatively easy to find your way around the city once you understand it.

First of all the lake is always east.

The Corner of State & Madison Street is the 0, 0 point of the grid. Going north from there the address increases by 100 North each block. For instance State & Grand Avenue is 600 North (6 blocks north of Madison). Similarly each block south of Madison increases by 100 South, ie Harrison and State is 600 South (6 blocks south of Madison).

The East/West addresses work the same way., increasing as you walk in the respective direction. So if you are at 400 West and as you walk the adresses are decreasing, you are going east. If you are are at 100 East and the the adresses are increasing you are going east and eventully you will end up in the lake.