at . The route begins where the roadway from Big Bend National Park's headquarters reaches the park's western entrance, and then proceeds a short distance to Study Butte. At Study Butte, SH 118 intersects FM 170 to Terlingua and Lajitas, and then proceeds along the Rio Grande to Presidio. Although the area around Study Butte is mountainous, the route through much of southern Brewster County is composed of long, straight stretches through arid ranch land as the road slowly climbs in elevation as its distance from the Rio Grande increases. Between Study Butte and Alpine, there are no major intersections, only junctions with unpaved county roads serving ranches and roads into remote residential subdivisions. Beyond a roadside picnic table near Crossen Mesa past the entrance to Elephant Mountain Wildlife Management Area, the road begins to enter the Davis Mountains. The road then becomes winding as it passes through the mountainous terrain. In this portion, there is another group of roadside picnic tables with a view of Cathedral Mountain. The road at one hill near Alpine has tight turns and steep grades as the road approaches the plateau where Alpine is situated. There is a U.S. Immigration and Customs Enforcement checkpoint south of Alpine. The road enters Alpine as South Walker Street passing along the eastern edge of Alpine Hill. SH 118 then makes a left and right curve to move one block further west on South Cockrell Street to pass along the western side of Sul Ross State University's Jackson Field football stadium. The road then crosses the Union Pacific Railroad and intersects U.S. Route 67 and U.S. Route 90. US 67 and US 90 overlay each other, and their route through the central part of the city passes along two one-way two-lane streets one block from each other. SH joins this overlay, with its northbound route following west on East Avenue E toward Marfa and its southbound route one block south on East Holland Avenue toward Marathon and Fort Stockton. SH 118 leaves the overlay going northward at North Fifth Street. On the city's north side, SH 118 leaves the street grid and intersects State Highway 223, a short highway passing around Alpine's northeastern quadrant to US 67 and US 90 at Sul Ross State University. SH 118 then crosses the South Orient Rail Line and passes by Alpine Casparis Municipal Airport before leaving town following a straight stretch