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:
SamTrans discontinued its last remaining express route, KX, by merging it into route 398 on August 5, 2018. Since then, the SamTrans board adopted the Express Bus Feasibility Study on December 5, 2018. The agency recommended launching six new express routes, starting with two pilot routes scheduled to begin in summer 2019. One route began service on schedule, but the other began service five years late. The first route, <span style="color:green;">FCX</span>, travels between San Francisco and Foster City along US 101. Route <span style="color:green;">EPX</span> provides service between San Bruno and East Palo Alto.
An early-morning weekday express route with limited trips, separate from the pilot program, was introduced on February 11, 2019. Route <span style="color:green;">713</span> provided replacement service for BART between 4:00 am and 5:00 am while seismic retrofit work was performed in the Transbay Tube. It currently runs between the Salesforce Transit Center and Millbrae Intermodal station via SFO Intl. Airport. This route was made a permanent addition.
The first new express route, designated <span style="color:green;">FCX</span>, started service on August 19, 2019. <span style="color:green;">FCX</span> 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.
The next two express routes began in 2024, one serving between San Francisco/San Bruno and East Palo Alto (<span style="color:green;">EPX</span>). The other, <span style="color:green;">PCX</span>, serves Pacifica while serving stops at bus pads along the CA-1 freeway.
These bus lines are SamTrans lines that serve the northern and coastal parts of San Mateo County. These lines are identified with a "<span style="color:blue;">1</span>" in the first digit of the three digit line number and designated as serving BART.
These bus lines are SamTrans lines that the central and southern portions of San Mateo County. These lines are identified with a "<span style="color:red;">2</span>" in the first digit of the three digit line number and designated as serving Caltrain.
These SamTrans bus routes serve multiple areas in San Mateo County. These routes were at one time identified with a "<span style="color:green;">3</span>" in the first digit of the three-digit route number and designated as serving both BART and Caltrain, although the <span style="color:green;">397</span> is the only remaining route with the number "3" in the first digit. Route <span style="color:green;">292</span> is an exception.
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.