The Fort Collins Municipal Railway operated streetcars in Fort Collins, Colorado, from 1919 until 1951. Since 1984, a section of one of the former routes has been in operation as a seasonal heritage streetcar service, under the same name, running primarily on Spring and Summer weekends. The heritage service is operated by volunteers from the Fort Collins Municipal Railway Society (FCMRS). The streetcar in use on the heritage line, Birney "Safety" Streetcar No. 21, is listed on the National Register of Historic Places.
Electric streetcar service in Fort Collins began on December 29, 1907. The first local street railway service had actually begun on August 8, 1907, temporarily using a steam locomotive borrowed from the Colorado and Southern Railway, hauling four elderly passenger coaches, on a newly constructed single-track line along Mountain Avenue. True electric trolley/streetcar service was inaugurated with the formal dedication of the new street railway system, on December 29 of the same year. The owner and operator was the Denver and Interurban Railroad (D&I), a subsidiary of Colorado & Southern Railway. The system struggled financially, its light ridership making it no longer economically viable as a private venture. The D&I itself soon went into receivership, and abruptly ceased operation of its Fort Collins trolley system, on the night of July 10, 1918. This left the town without public transportation service. It was proposed that the city purchase the system and restore service. This was approved by the city council and, in January 1919, in a vote by the citizens, and the Fort Collins Municipal Railway (FCMR) was formed. Rolling stock was not part of the deal, so four new Birney-type streetcars were purchased from the American Car Company, numbered 20–23, arriving on May 24, 1919. Within one to two weeks of that date, streetcar service in Fort Collins was restored. A fifth Birney car, No. 24, was purchased in 1920 from the Cincinnati Car Company, and in 1924 two secondhand Birneys (built in 1922 by American Car) were acquired from the Cheyenne Electric Railway Company, becoming Fort Collins cars 25–26. In the mid-1940s, cars 24 and 25 were replaced by two other Birneys, bought used from the Virginia Electric Power Company. The system operated three routes and ran on a 20-minute schedule. During its period of municipal ownership, 1919–1951, Birney-type cars made up the entire fleet, with a total of just five to seven cars (numbered in the range 20–26) on the active roster at any time. It was the last all-Birney streetcar system in North America.