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
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 Chicagoby Don Hayner and Tom McNamee that might have the answer