The Chicago blues is a form of blues music that developed in Chicago, Illinois by adding electrically amplified guitar, drums, piano, bass guitar and sometimes saxophone to the basic guitar/harmonica Delta blues. The music developed mainly as a result of the "Great Migration" of poor black workers from the South into the industrial cities of the North such as Chicago in particular, in the first half of the twentieth century.
Chicago Blues has a more extended palette of notes than the standard six-note blues scale; often, notes from the major scale are added, which gives the music a more "jazz feel" whilst still being in the confines of the blues genre. This is not, however, as prominent as Texas blues, which contains many other notes such as the major 3rd and major 6th. Chicago blues is also known for its heavy rolling bass.
Another notable point is that Chicago blues contains many dominant 9th chords, and the scales usually contain 9th notes. Note that a 2nd is the same as a 9th (The notoriously confusing '9=2' that many chord charts show is showing this fact), and this is especially emphasized on guitar, which it is much more difficult to span octaves, versus a piano.

Notable Chicago blues musicians
Below is a list of notable Chicago blues musicians (and groups) alphabetized by first name (or stage name):

Big Bill Broonzy
Big Maceo Merriweather
Big Walter Horton
Blue Plate Special
Bonnie Lee
Boston Blackie
Buddy Guy
Charlie Musselwhite
Carey Bell
Charlie Love
Corky Siegel
David "Honeyboy" Edwards
Detroit Junior
Dion Payton
Earl Hooker
Eric Clapton
Elmore James
Erwin Helfer
Fenton Robinson
Freddie King
Harry Binford
Homesick James
Hound Dog Taylor
Howlin' Wolf
Hubert Sumlin
J.B. Lenoir
Jimmy Cotton
Jimmy Dawkins
Jimmy Johnson
Jimmy Rogers
John Brim
John Primer
Johnny Shines
J.T. Brown
Junior Wells
Kansas Joe McCoy
Koko Taylor
Kokomo Arnold
Little Walter
Lonnie Brooks
Lovie Lee
Luther Allison
Lurrie Bell
Magic Sam
Magic Slim
Mighty Joe Young
Mike Bloomfield
Muddy Waters
Otis Rush
Otis Spann
Papa Charlie McCoy
Paul Butterfield
Pinetop Perkins
R.P. Michaels
Robert Nighthawk
Robert Lockwood Jr.
Ronnie Baker Brooks
Robert Johnson
Sammy Fender
Snooky Pryor
Son Seals
Sonny Boy Williamson
Sunnyland Slim
Vince Agwada
Wayne Baker Brooks
Willie Dixon
Willie Kent