Pace bus routes usually fall in one of the following five categories.
Traditional Suburban - basic transit routes in suburbs adjacent to Chicago. Most routes were originally created as bus routes from the 1920's through the 1950's. In a few older suburbs, the bus routes replaced streetcar routes introduced in the 1890's. Those Pace routes are generally numbered in the 200's or 300's.
Satellite City - transit routes in the four "satellite" cities of Joliet, Aurora, Elgin, and Waukegan, all of which developed streetcar routes beginning in the late 1800's, All streetcars were replaced with buses in the 1930's or 1940's. These Pace routes are all numbered in the 500's.
Rush Hour Feeder - introduced by individual suburbs in the 1970's, later expanded by RTA and Pace. During the morning rush hours, buses transport suburban residents from their neighborhoods to the Metra train stations, connecting with Chicago bound trains. In the afternoon rush hours, buses meet trains arriving from Chicago, and transport the suburban residents back home. Most feeder routes are in Du Page County, while very few all day bus routes exist in that area.
Reverse Feeder - a few rush hour routes travel from outlying Metra stations to suburban office and industrial areas during the morning rush hours, and back to the stations in the afternoon rush hours.
Reverse Commuter - one of the larger growth areas for Pace in recent years. These bus routes often operate via expressways, connecting CTA rapid transit terminals with suburban office and industrial areas, enabling city residents without automobiles to commute to where the jobs are.
Routes 204-291 (Northwest/North Shore)
Routes 301-336 (West)
Routes 347-372 (South)
Routes 379-397 (Southwest)
Routes 401-416/430-442 (Miscellaneous Northwest/West)
Routes 421-426 (North Shore/Wilmette)
Routes 448-465 (Feeder Routes South/Downers Grove)
Routes 470-476 (Highland Park)
Routes 500-512 (Joliet)
Routes 521-540/559 (Aurora)
Routes 541-558 (Elgin)
Routes 560-582 (Waukegan)
Routes 590-598 (Dial-A-Ride)
Routes 600-641 (Miscellaneous Northwest/West)
Routes 641-689 (Du Page County Feeder Routes)
Routes 690-699 (Miscellaneous/Northwest)
Routes 700-722 (Du Page County Routes)
Routes 720-747 (Miscellaneous Discontinued Routes)
Routes 750-791 (Miscellaneous Routes)
Routes 800-804 (Fox River Valley Interurban)
Routes 805-830 (Miscellaneous)
Routes 831-838 (Joliet/Interurban)
Routes 850-999 (Miscellaneous)