It is common for streets that go through Chicago and beyond into the suburbs to change names once they pass the Chicago city limits. Within the city, however, most (not all) streets typically have the same name when crossing between the east and west or north and south sides. However, nearly every north/south street meeting the following criteria changes names when it crosses between the north and south side of chicago, south of roughly Division:
Any north south street, east of Ashland, which is not a thoroughfare (ie, a street who's E/W coordinates are a multiple of 400):
1600W:Ashland<=>Ashland
1500W:Laflin<=>Greenview
1400W:Loomis<=>Southport
1300W:Lakewood<=>Throop
1200W:(Racine<=>Racine)
1100W:Kenmore<=>Aberdeen
1000W:Sheffield<=>Morgan
900W:Dayton<=>Peoria
800W:(Halsted<=>Halsted)
700W:Orchard<=>Union
600W:Larrabbee<=>Jefferson
500W:Cleveland<=>Canal
East of 500W the north end of streets is in or just north of downtown, but even those change
400W:Sedgwick<=>Stuart (I don't believe Stuart is a thoroughfare)
300W:Franklin<=>Princeton
200W:Wells<=>Wentworth
100W:Clark (doesn't really exist south of 22nd)
0E/W (State<=>State)
100E:(Michigan<=>Michigan) (Michigan is a thoroughfare)
200E:St Claire/Mies Van Der Roe<=>Indiana
300E:Fairbanks/Columbus<=>Giles/Calumet
400E:McClurg<=>King (McClurg isn't really a thoroughfare)
500E:Streeter<=>Vincennes
Nothing east of Streeter exists on the north side due to the curvature of the lake.
Now, west of Ashland, this is not observered at all, to just name the starting few:
1700W Paulina<=>Paulina
1800W Wood<=>Wood
1900W Wolcott<=>Wolcott
2000W Damen<=>Damen
...etc
Why do the streets east of Ashland (~2.5 miles) all change names between the north and south sides, but the rest of west of Ashland (using roughly Harlem as the west edge: ~7+ miles) not observe the same convention?
Streetwise Chicago
by Don Hayner and Tom McNamee that might have the answer