State Highway 16 (SH 16) is a south–north state highway in the U.S. state of Texas that runs from Zapata on the boundary with Mexico to U.S. Highway 281 south of Wichita Falls. It is the longest state highway in Texas at almost , but is only the ninth-longest of any highway classification in the state. Route description SH 16 begins at an intersection at US 83 in Zapata. The route continues through south Texas ranchlands, then to the north through San Antonio's far south side. The routes enters San Antonio from the southeast, and goes around the west side of the city concurrent with Interstate 410. The route veers to the northwest as it passes through Bandera, Kerrville, and Fredericksburg, and then reaches the Texas Hill Country. After passing through the cities of Comanche and Llano, it continues north through ranchland and farms. Its next intersection is with I-20 south of the town of Strawn. It continues to the northwest, wrapping around the northern and eastern sides of Possum Kingdom Lake. It reaches an intersection with US 380 in the town of Graham. In North Texas, the highway reaches its northern terminus between Antelope and Windthorst, almost 542 miles from its starting point. Previous routes SH 16 was one of the original twenty five state highways proposed on June 21, 1917, overlaid on top of the Fort Worth-Oklahoma Highway. From 1917 the routing mostly followed present day Interstate 35W from Fort Worth to Denton. It continued on, routed along present day Interstate 35 from Fort Worth through to Oklahoma. A spur, SH 16A, went from Denton to Dallas. On March 18, 1919, the route and SH 16A were cancelled, as both routes became part of SH 40. SH 16 was then reassigned to the future route of U.S. Highway 181 (which was routed over it in 1926) from San Antonio to Corpus Christi on August 21, 1923. SH 16 then went west on SH 44 to Robstown, south on U.S. Highway 77, and west on SH 285. This route replaced portions of SH 9 and SH 12. On January 20, 1930, SH 16 Spur was created in Sinton. SH 16 was extended on January 19, 1932, following SH 9 to Brady, replaced SH 107 to Santa Anna, following SH 7, SH 4, SH 30, and SH 18 to Sagerton, then replaced SH 51 to the Oklahoma State line. On