List of SamTrans bus lines

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.

Route numbering scheme

 * Notes

Express routes
SamTrans discontinued its last express route, KX, by merging it into line 398 on August 5th 2018. Since then, the samTrans board adopted the Express Bus Feasibility Study on December 5, 2018. The agency has recommended launching six new express routes, starting with two pilot routes scheduled to begin in summer 2019. The first route will travel between San Francisco and Foster City along US 101, and the second route will travel between San Francisco (Divisadero and Geary) and Palo Alto via I-280 and 19th Avenue in San Francisco. In the second phase, two new express routes will take advantage of managed lanes that will be added to US 101; one will provide service between San Bruno and East Palo Alto, and the other will run between San Mateo (via park-and-ride) and downtown San Francisco. The fifth and sixth new express routes will provide service between San Mateo and western San Francisco, and between Burlingame and downtown San Francisco.

An early-morning weekday express route with limited trips, separate from the pilot program, was introduced on February 11, 2019. Route 713 provides replacement service for BART between 4:00 am and 5:00 am while seismic retrofit work is performed in the Transbay Tube. It runs between the Salesforce Transit Center and Millbrae station via SFO.

The first new express route, designated FCX, started service on August 19, 2019. FCX operates two trips in each direction with headways of approximately 30 minutes during peak weekday commute hours, using recent buses that feature onboard Wi-Fi.

A new express route EPX was created on February 12, 2024.

Local bus lines that serve North County
These bus lines are SamTrans lines that serve the northern and coastal parts of San Mateo County. These lines are identified with a " 1 " in the first digit of the three digit line number.

Local bus lines that serve South County
These bus lines are SamTrans lines that the central and southern portions of San Mateo County. These lines are identified with a " 2 " in the first digit of the three digit line number.

Local bus routes with both BART and Caltrain connections
These SamTrans bus routes connect to both BART and Caltrain stations in San Mateo County. These routes are identified with a " 3 " in the first digit of the three-digit route number, although the " 397 " is the only remaining route with the number "3" in the first digit. Route 292 is an exception. Route ECR also falls into this category.

School-oriented local bus lines
These bus lines are community bus service that mainly serve schools. They have a limited number of runs, typically one in the morning and one in the afternoon. This may vary per route.