This is a list of bus routes operated by the San Mateo County Transit District (SamTrans) primarily in San Mateo County of the San Francisco Bay Area, in the state of California.
Notes:
- †: San Francisco stops restriction applies
- Northbound (from San Mateo County): SamTrans cannot pick up northbound passengers at San Francisco stops
- Southbound (to San Mateo County): Passengers boarding in San Francisco may not disembark in San Francisco
- NB – northbound, SB – southbound
- Sunday service is run during most holidays.