State Route 61 (SR 61) is a California, United States, highway which runs through Alameda and along the Oakland International Airport. The western terminus is with State Route 260 at Webster Street in Alameda, and it runs along east Central Avenue and Encinal Avenue until reaching Broadway. It goes south along Broadway, then east along Otis Drive until crossing off the island of Alameda on the Bay Farm Island Bridge. It then follows Dolittle Drive near the Oakland International Airport until it reaches State Route 112 at Davis Street in San Leandro.

As legislatively defined, Route 61 extends as far north as Albany and as far south as the Dumbarton Bridge's east approach. Only the portion between Routes 260 and 112 is constructed; the unbuilt remainder of the route exists today either as open San Francisco Bay or wetlands. This route would likely have sat atop landfill; as public opinion shifted against filling in the bay, completing the remaining portions of Route 61 also fell out of favor. Route 87 is another highway once proposed to traverse present-day wetlands and open water.

Routes 112 and 260 are "hidden" routes that, despite having legal descriptions separate from Route 61, are signed as part of Route 61. Route 112 runs as Davis Street to State Route 185 (East 14th Street) in San Leandro. Route 260 goes to (but does not intersect with) Interstate 880 in Oakland through the Posey and Webster underwater tunnels.

Route 61 is part of the California Freeway and Expressway System.

The route begins at SR 185 in San Leandro. It then interchanges with Interstate 880. It then continues northward and enters the city of Oakland for a short while and crosses the San Leandro Bay via a drawbridge. It then winds its way northward through the city of Alameda. It then goes under the Oakland Estuary via the Posey and Webster Street Tubes; it then reenters the city of Oakland, where it meets its north end at 7th Street.

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, and do not necessarily reflect current mileage. The entire route is in Alameda County.