List of AC Transit routes

AC Transit operates 175 bus lines throughout the East Bay, including two lines under the Broadway Shuttle name. While AC Transit administers Dumbarton Express, it transferred operation of that service to MV Transportation effective 19 December 2011. Extensive local service connects 15 cities in Alameda and Contra Costa Counties and Milpitas in Santa Clara County. Transbay service is provided to San Francisco, San Mateo County, and Palo Alto in Santa Clara County.

AC Transit bus routes are arranged in six categories (five numbered, one lettered). Since its inception in 1960, AC Transit has used both numbers and letters to distinguish routes. Many Transbay rail lines were inherited from the Key System and converted to bus routes, and AC Transit continued to use letters to identify the routes. Many Transbay routes continue to follow the original Key System routings to some degree. The number and letter ranges listed below do not mean that all numbers or letters with a range are in use.

Numbered routes operate within the East Bay:

One- and two-digit route numbers are sometimes used as a "base" number for three-digit route numbers. For example, Route 339 is "based" on Route 39.

Lettered routes (A to Z) provide Transbay service (i.e., service across a bridge) between the East Bay and San Francisco, San Mateo, and Santa Clara Counties.

Suffixes (also lettered) are used on some local and Transbay routes to distinguish different routings. Currently, A, B, C, L, M, R, S, and X are used. Some suffixes have special meanings:

Supplemental numerical suffixes are used to differentiate route variations for lines that already use a lettered suffix. This is the case with the NX lines listed above.

Note: Routes listed below are current as of March 26, 2017.

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