While at a conference in San Francisco last week, I was surprised to see a former Twin Cities trolley rolling down Market Street. The city is best known for its homegrown cable cars, but it also operates a fleet of historic streetcars that bear the colors of defunct trolley lines in cities across North America, including the Twin Cities. They run from the Castro neighborhood to Fisherman's Wharf, and while they no doubt appeal to tourists, they're clearly an element of the Muni public transportation system and its nonprofit partner, the Market Street Railway. This streetcar, No. 1071, is one of 11 built for the Twin City Rapid Transit system in the 1940s, and later shipped to Newark, N.J., when the buses replaced the last Twin Cities trolley in 1954. Muni bought those streetcars in 2010, and No. 1071 went into service as the only one painted in the original gold-and-green Twin City color scheme.