The WTA is funded by a 0.6% sales tax within the Whatcom County public transportation benefit area (PTBA) and grants from the state and federal governments.

Service began on January 1, 1984, using equipment bought from the Bellingham municipal transit system after a countywide authority was established a year earlier.

[4][better source needed] The streetcar system continued to be the main form of public transportation until the 1920s and 1930s when automobiles and buses began to take over.

In 1971, Bellingham took over a failing private bus company, establishing a municipal transit system funded by a 0.3% sales tax introduced in 1975.

[3] The "GO Lines" are four corridors where local service combines for 15-minute headways on weekdays and are branded with a specific color by the WTA beginning in 2005.

[11] WTA Route 80X, known as the County Connector, is an inter-county route operated by the WTA and Skagit Transit that makes 9 daily roundtrips on weekdays and 5 daily roundtrips on Saturdays and Sundays between Bellingham Station and Skagit Station in Mount Vernon, with intermediate stops at park and rides along Interstate 5.