CHICAGO — Sarah Jindra is bringing back her “Street School with Sarah” segment that became a hit during the COVID-19 pandemic. The first topic: the Chicago Grid!

You see these numbers on major street signs, even on CTA platforms. The numbers indicate exactly where you are. But if you don’t know the Grid, these numbers mean nothing to you.

The center of the Grid, 0-0 which is State Street and Madison Street. So why is this the center of the grid?

Northwestern University professor Bill Savage explains:

“State and Madison are the zero points on the grid because a reformer named Edward Brennan campaigned for years and years to make the addresses logical. He proposed State/Madison as the center point with a grid of originally 1000 to a mile, but 800 to a mile was the old section lines from back when it was mapped in the 1830s.”

So that’s what they went with. Enacted in 1909, every 800 block, or eight city blocks, would be another mile from the center point — turning the city into a grid.

So heading north from our center, Chicago Avenue is a mile away at 800 North, 1600 North, or North Avenue, is two-miles away, 2400 North, or Fullerton, is three miles away. If you’re at Touhy Avenue, 7200, just divide by 800 and you’ll know that you’re about nine miles north of Madison.

It’s the same going west from State Street: 800 West, or Halsted, is a mile away, 1600 West, or Ashland, is two miles away and that continues west.

East of State Street it’s the same with Cottage Grove, Stony Island and so on.

But, going south of State and Madison, the 800 rule is broken a bit. A mile south of there should be 800 south or eight city blocks, but it’s actually 1200 south, or Roosevelt. Twelve blocks away, the next mile is 10 blocks from there, 2200 South, or Cermak. The next mile is nine blocks from there at 3100 South.

“The East West streets on the South Side were made numerical streets in the 1880s and they didn’t want to bother changing it because the addresses lined up with the street numbers. So even the mile things aren’t right, the addresses are right. So we kind of half did it,” Savage explained. 

South of 31st Street, our 800’s rule picks back up. A mile after that is 3900, add on 800, next mile is 4700, the next is 55th or Garfield and it continues south.

“This knowledge of the city makes you an insider makes you feel like you own the city and that’s an important thing because Chicagoans invest a lot of emotion in this place and the grid is part of that,” Savage said.