Texas elevation map

Follow I-10 west and the climb is easy to read. Houston sits at 80 feet on the coastal plain. San Antonio is at 650 feet, right at the foot of the Balcones Escarpment. West of the city the road climbs onto the Edwards Plateau and stays above 1,700 feet for 300 miles, crosses the Pecos, and reaches El Paso at 3,740 feet — a gain of about 3,700 feet over roughly 800 miles.

The northern route rises faster. From Fort Worth at 653 feet, US-287 and I-27 climb the Rolling Plains and then run into the Caprock Escarpment, which lifts the road several hundred feet in a few miles onto the Llano Estacado. Once on top, Lubbock is 3,202 feet and Amarillo 3,605 feet, and the surface stays close to dead flat until it leaves the state.

Eight of the ten highest summits in Texas stand in one small range in Culberson County, a fossil reef pushed up on the New Mexico line and protected as Guadalupe Mountains National Park. Guadalupe Peak carries a stainless-steel pyramid at the top and is reached on a steep 8.4-mile round trip from Pine Springs; El Capitan, the cliff visible for 50 miles along US-62/180, is the range's landmark rather than its high point.

The other peaks are volcanic. Mount Livermore is the crown of the Davis Mountains and sits on private land; Mount Locke beside it carries the McDonald Observatory domes, reached by what is usually called the highest public road in Texas. Emory Peak is the summit of the Chisos, and because the Rio Grande runs at roughly 1,800 feet through Big Bend National Park, the park holds about 6,000 feet of relief inside one boundary.

The Balcones Escarpment is a fault zone, not an eroded edge. It runs in an arc from Del Rio through San Antonio and Austin to near Waco, and lifts the Edwards Plateau a few hundred feet above the coastal plain. I-35 follows the base of it, which is why the ground west of that highway is hilly and rocky and the ground east of it is flat farmland — and why the Hill Country begins where it does.

The Caprock Escarpment is the eastern rim of the Llano Estacado, the high tableland covering the South Plains and southern Panhandle. Where rivers have cut back into it the drop is dramatic: Palo Duro Canyon is about 800 feet deep, and Caprock Canyons exposes red beds several hundred feet below the plain. The Llano Estacado surface itself rises gently westward from roughly 2,700 feet at the Caprock to over 4,000 feet near the New Mexico line, and is one of the flattest large surfaces in North America.

The whole 350-mile shoreline is the state's low point. The coastal counties sit within a few feet of sea level, and the barrier islands — Galveston, Mustang, Padre — are little more than sand a few feet above the water, which is why storm surge pushes miles inland. After the 1900 hurricane, Galveston raised its ground level behind a new seawall, lifting buildings and pumping in fill to a maximum of about 17 feet near the wall and grading down toward the bay.

Elevation also explains the climate split described on the climate map: Amarillo and Lubbock get hard freezes and snow at over 3,000 feet while Brownsville, at 33 feet, rarely freezes at all. For contour detail rather than summary figures, see the topographic map.