A signal station was erected on Telegraph Hill in 1849 from which to observe the incoming vessels, a tall pole with movable arms was used to signal to the people in the town below whether sailing vessels or the sidewheel vessels of the Pacific mail were passing through the Golden Gate. In September 1853, the first telegraph in California, which extended eight miles to Point Lobos, was stationed here, giving the hill its name.

Citation from California Office of Historic Preservation