Union Street is an east–west street in San Francisco.^[1] It starts out near the Embarcadero waterfront, with a half-block gap on Telegraph Hill before resuming near Montgomery Street, then runs through Russian Hill and a shopping district in Cow Hollow, ending in the Presidio. According to some,^[who?] Union Street also marks the dividing line between Cow Hollow and Pacific Heights to the south.^[2]

It is the only east–west street that allows two-way traffic to traverse Russian Hill (all others have gaps or one-way segments). The Muni 45 Union/Stockton and 41 Union bus lines, both utilizing Union Street, are the only Muni bus lines that cross Russian Hill east-west.