The twin cities of Champaign and Urbana, Illinois, are located approximately 125 miles south of Chicago.  They comprise a metropolitian area of over 100,000 and are the home of the University of Illinois
The Champaign-Urbana Mass Transit District started service in the summer of 1971, taking over from a private company.  They started with 15 new GMC T6H-4521 buses, plus 10 1960 TDH-4517 buses obtained from the Greater Peoria (IL) MTD.  These days, the size of the fleet has more than doubled, and uses 40-foot buses and articulated buses.
This pic is of my favorite bus from the original 1971 fleet, 4504.  Taken at the end of the line of the "ILLI BUS", the Community Center at Orchard Downs (U of I Married Student Housing) in early 1972.
A unique feature of C-UMTD when it first started was that the routes had colors instead of numbers or names, and the buses were painted in the colors of the route!
The breakdown was as follows:
4501-4504: painted white for use on the Illi Bus and backup for the colored routes
4505-4506: Red
4507-4508: Orange
4509-4510: Lavender
4511-4512: Green
4513-4514: Blue
4515: Yellow

The 10 buses from Peoria at first kept their Peoria numbers (1001-1010), but shortly thereafter, 1010 was painted green (since the Green line required 3 buses, and renumbered 4516. 1009 was painted Blue and renumbered 4517 (though I never remember seeing it on the Blue line or anywhere else). 1001-1008 kept their Peoria numbers until the fall of 1972, when they were renumbered 4518-4525 (in order, i.e. 1001=4518, 1002=4519, etc.)  My favorite from this group was 1005 (4522)
Click here for more C-UMTD pics
For more info, try the following links:
Official C-UMTD page
C-UMTD all time roster page at Bus Rosters on the Web
This page created 03/08/04