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 - as many suburbs grew, with ridership growth at many commuter rail stations, traffic and parking congestion became a challenge at many stations. Naperville is the suburb most notable for its growth. These bus routes were introduced by individual suburbs beginning around 1974, later expanded by RTA and Pace. During the morning rush hours, buses would 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 were in Du Page County, while very few all day bus routes exist in that area. In 2020, due to the covid-19 pandemic, most of these routes were indefinitely suspended. It is uncertain, if Pace funding in the future would provide for restoration of any of these routes.
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)
Historic Predecessors: UNITED MOTOR COACH/NORTRAN
ROUTES 301-336 (WEST)
Historic Predecessors: CHICAGO & WEST TOWNS RAILWAY/WEST TOWNS BUS CO.
ROUTES 347-372 (SOUTH)
Historic Predecessors: SOUTH SUBURBAN SAFEWAY LINES
ROUTES 379-387 (SOUTHWEST)
Historic Predecessors: SUBURBAN TRANSIT SYSTEM
ROUTES 390-398 (UNITED PARCEL SERVICE)
ROUTES 401-416/430-442 (MISCELLANEOUS NORTHWEST/WEST)
ROUTES 421-426 (NORTH SHORE/WILMETTE)
Historic Predecessors: GLENVIEW BUS CO./WILBUS
ROUTES 448-465 (PRE-RTA FEEDER ROUTES)
ROUTES 470-476 (HIGHLAND PARK)
ROUTES 500-512 (JOLIET)
Historic Predecessors: CHICAGO & JOLIET ELECTRIC RAILWAY/JOLIET CITY LINES
ROUTES 521-540/559 (AURORA)
Historic Predecessors: AURORA ELGIN & FOX RIVER ELECTRIC/AURORA CITY LINES
ROUTES 541-558 (ELGIN)
Historic Predecessors: AURORA ELGIN & FOX RIVER ELECTRIC/ELGIN CITY LINES
ROUTES 560-582 (WAUKEGAN)
Historic Predecessors: NORTH SHORE LINE/WAUKEGAN-NORTH CHICAGO TRANSIT
ROUTES 590-599 (DIAL-A-RIDE)
ROUTES 600-641 (MISCELLANEOUS NORTHWEST/WEST)
ROUTES 641-689 (VILLAGE SPONSORED FEEDER ROUTES/DU PAGE COUNTY)
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)
Historic Predecessors: AURORA ELGIN & FOX RIVER ELECTRIC/AURORA-ELGIN BUS LINE
ROUTES 805-830 (MISCELLANEOUS)
ROUTES 831-838 (JOLIET/INTERURBAN)
Historic Predecessors: CHICAGO & JOLIET ELECTRIC RAILWAY/BLUEBIRD COACH LINES
ROUTES 850-999 (MISCELLANEOUS)