Chicago is sometimes called “Chi-town.” “Chi” (for Chicago) is pronounced “shy.”
 
“The ‘Chi’ town men who were going down to St. Louis” was printed in the Butte (MT) Inter Mountain on November 23, 1901. “Chi-town” was used in CB slang in the 1970s, but the nickname had already long been in use.
   
 
Wikipedia: Chicago
Chicago (/ʃᵻˈkɑːɡoʊ/ or /ʃᵻˈkɔːɡoʊ/; shi-kah-goh) is the third most populous city in the United States. With over 2.7 million residents, it is the most populous city in the state of Illinois and the Midwestern United States, and the county seat of Cook County. The Chicago metropolitan area, often referred to as Chicagoland, has nearly 10 million people and is the third-largest in the U.S.
 
Wikipedia: List of nicknames for Chicago
“Chi-Town” or “Chitown” (/ˈtʃaɪtaʊn/ chai-town to /ˈʃaɪtaʊn/ shy-town) – Often used in CB slang as noted in the C.W. McCall song “Convoy”.
“The Chi” (pronounced “shy”) – Short for the word ‘Chicago’
 
Chronicling America
23 November 1901, Butte (MT) Inter Mountain, “Sporting,” pg. 4, col. 1:
The “Chi” town men who were going down to St. Louis to buy up the Missouri river town for the purpose of pulling off the fight there were thrown completely in the air after all their boastfulness.
 
Chronicling America
14 August 1902, Butte (MT) Inter Mountain, pg. 8, col. 6:
There were seven hits recorded against him, but the way in which the lanky boy from “Chi-town” turned on the steam in the eighth and ninth innings sent a streak of yellow down the backs of the police-protected players.
 
Old Fulton NY Post Cards
23 August 1902, Rochester (NY) Democrat and Chronicle, “Still Hunting the Murderer,” pg. 14, col. 5:
He was “dead stuck” on “Chi Town,” as he called Chicago.
 
Old Fulton NY Post Cards
11 October 1902, Rochester (NY) Democrat and Chronicle, pg. 16, col. 6:
SENT CROOK ON HIS WAY.
James Artery, a “Chi Town” Professional, Hustled Out of the City.
   
Old Fulton NY Post Cards
8 June 1918, Buffalo (NY) Courier, pg. 9, col. 3:
There is a man in Chi town.
(...)
Copyright, Chicago Herald-Examiner.
 
8 December 1926, Variety, pg. 9, col. 5:
2nd Vita Bill in Chi;
Town’s Pie for Talkers
 
17 October 1935, Atlanta (GA) Daily World, pg. 5, col. 8:
TUSKEGEE CLUB HAS SPIRIT IN CHI’ TOWN
 
Google Books
The Complete CB Handbook
By Jethro Koller Lieberman and Neil S. Rhodes
New York, NY: Avon
1976
Pg. 341:
Chicago—Big C; Big Windy; Cattle Town; Chi Town; Shy Town; Windy City.
 
OCLC WorldCat record
Growing up in Chi-Town : a story of the 1960s
Author: Joseph J Robinson
Publisher: [Chicago, IL] : The Committee, ©1980.
Edition/Format:   Print book : Biography : English
 
OCLC WorldCat record
Chi-town showdown
Author: Esquires (Musical group : Milwaukee); Marvelows (Musical group)
Publisher: San Francisco, Calif. : Solid Smoke, [1982]
Edition/Format:   Music LP : English
 
OCLC WorldCat record
Chi town
Author: Norbert Blei
Publisher: Evanston, Ill. : Northwestern University Press, 2003.
Edition/Format:   Print book : Biography : EnglishView all editions and formats
Database: WorldCat
Summary:
The final work of the “Chicago Trilogy”, this collection of non-fiction tales reveals Sandburg’s “city of the big shoulders” concret and neon; uptown and downtown. The stories evoke a vanished Chicago, a city of gritty and colourful neighbourhoods and their characters.
 
Urban Dictionary
chi town
slang name for Chicago
Let’s roll into chi town
by AC December 09, 2003