California State Route 61

State Route 61 (SR 61) is a state highway in the U.S. state of California, running along the eastern edge of Oakland International Airport and through Alameda. Two additional "hidden" state highways, State Route 112 (SR 112) and State Route 260 (SR 260), are also signed as part of SR 61, despite having legal descriptions separate from Route 61.

SR 112 runs along Davis Street from State Route 185 (East 14th Street) west to Doolittle Drive in San Leandro. SR 61 proper then follows Doolittle Drive north near the eastern boundary of Oakland International Airport to Bay Farm Island and across the Bay Farm Island Bridge to Alameda Island. SR 61 then runs on various city streets in Alameda to Webster Street. SR 260 then goes from Webster Street through the Posey and Webster Street tubes to near Interstate 880 in Oakland. Though some maps mark the highway as continuous along Alameda's Webster Street, control of the segment between Central Avenue and Atlantic Avenue was relinquished to the city and is thus no longer officially part of the state highway system. As of 2012, a sign indicating SR 61 East near the I-880 interchange was replaced with an SR 112 shield; it has been replaced with a SR 61 sign as of 2025.

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.