In Chicago, IL, why do most north/south streets change names east of Ashland on the north vs south side?

Question

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?

Answer 1

Really interesting question....

I went through about 8 sources. There are a lot of cool sources on how Chicago laid out it's north south east and west grids around the epicenter of State and Madison Streets in the heart of the Loop. I used to live off of Erie right across from the Playboy skyscraper. I ultimately had to google map the intersections you were talking about so I could visualize the question.

The answer is between 1909 and 1911 as Chicago tried to standardize addresses and street blocks, they also tried to standardize street names. This meant consolidating 100's of street names. Only they weren't consistent. Older better established parts of the city closer to the lake were more successful in resisting the name changes than were the more recently settled western parts of the city.