Mass transit in Denver began in 1871, when the Denver Horse Railroad Company started running horse-drawn coaches on tracks in the middle of downtown’s dirt streets. By the mid-1880s, the system, eventually called the Denver City Railway, had forty-five coaches and a sixteen-mile network of rails. In 1886, the Denver Tramway Company introduced America’s first and the world’s second electric streetcar system. By 1900, more than 150 miles of track crossed the city, while commuter rail lines connected Denver with Golden, Littleton, Boulder, and other places. Although private automobiles became more common after 1920, trolleys remained Denver’s primary public transportation through the World War II years. Denver Tramway began replacing some streetcar lines with bus routes as early as 1930, and that shift accelerated during and after World War II until the streetcars stopped running altogether by 1950. In the late 1960s, bus service also nearly collapsed as rising auto culture eroded ridership and pushed Denver Tramway toward financial ruin. The state legislature then created the publicly financed Regional Transportation District, which took control of the bus system in 1971 and has operated it ever since. In the 1990s, the Regional Transportation District launched a light-rail system to ease pressure on crowded freeways, returning Denver public transit in some respects to the same wheels-on-rails principle on which it had begun.