First post office in Runnels County. Named for Gap in Table Mountain. Established Feb. 14, 1878; used until transferred in 1882 to the town of Content 2 miles north. Last postmaster was A. A. Hanscomb. The one-room structure has hand-hewn cedar rafters, hand-made shingle roof and walls of roughly-hewn logs. Also served as a stop on the Round Rock to Buffalo Gap stage route. Cabin was recently restored.