Big Blue Bus (stylized, big blue bus) is a municipal bus service serving the city of Santa Monica and the greater Westside region of Los Angeles County. The service, operated by the city of Santa Monica, was founded on April 14, 1928 and throughout its existence has used a blue color scheme for its buses, leading to the Big Blue Bus nickname that would later become the official name of the agency. In 2021, the system had a ridership of 5,500,200, or about 22,500 per weekday as of the second quarter of 2022. Big Blue Bus receives funding from the Los Angeles County Metropolitan Transportation Authority (Metro) and offers connections to its Metro Bus and Metro Rail systems, but is operated independent from Metro.