Union Cemetery's name reflects the controversy that erupted in the Civil War, three years after the cemetery's beginnings in 1859. Pro- and anti- slavery feelings ran high in California, and the founders of the cemetery strongly opposed the secessionist sentiment that threatened the nation's unity. Because of a controversy over the cemetery's ownership, the state enacted its first cemetery legislation. Although its provisions did not affect Union Cemetery, the law of 1859 allowed for the incorporation of rural burial grounds. The state of California owned Union Cemetery from 1859 until 1962 when it was deeded to Redwood City.

California Registered Historical Landmark No. 816

Originally registered June 1, 1967. Plaque placed by the State Department of Parks and Recreation in cooperation with the Union Cemetery Association and Capitulus Redivivus Yerba Buena No. 1, A&HO of E Clampus Vitus, July 4, 1999,