Sisk, a farming community near Stephenville in central Erath County, was settled by Henry Clark in 1856 and was originally called Rockfalls. The name was changed to Sisk when the post office was established in 1903, with William T. Long as first postmaster. Mail service was discontinued in 1921, and the mail was sent to Johnsville. Sisk reported fifteen residents in 1910, but thereafter no further population figures were available. By the mid-1930s the community was no longer shown on county maps.