River Road FM-170

Presidio to Lajitas

West Texas · Texas · United States

Key measurements

Distance

49.8 miles

Elevation gain

3,431 ft

Elevation loss

3,677 ft

High point

2,862 ft

Low point

2,293 ft

Net change

-239 ft (2,580 ft to 2,341 ft)

Surface

Paved

Route type

point-to-point

Route Overview

Farm to Market Road 170, known locally as the River Road, is one of the most geographically striking stretches of asphalt in Far West Texas. Running southeast from the border town of Presidio to the desert settlement of Lajitas, the route directly parallels the Rio Grande as it carves through the Chihuahuan Desert.

Over its 49.8 miles, the road shifts from the wide floodplain of the Presidio Basin into the stark, volcanic canyons and uplands of Big Bend Ranch State Park. The landscape is defined by dark basaltic cliffs, abrupt arroyos, and limestone bluffs towering over the narrow green ribbon of the river corridor. With over 3,400 feet of cumulative elevation gain, the route climbs steeply out of river cuts onto high desert benches before dropping back down toward the river basin.

Key Segments & Geographic Transitions

River Road Canyons & Big Hill — Miles 0.6–49.8

Departing the flat agricultural bottomland around Presidio, FM 170 heads southeast toward the raw volcanic topography of the Solitario and the Bofecillos Mountains. As the road enters Big Bend Ranch State Park, the terrain immediately tightens. The route hugs the contoured cliffs above the Rio Grande, weaving through a succession of deep dry washes and low-water crossings.

The physical highlight of the segment occurs near Mile 36.4, where the highway rises sharply to its highest point at 2,862 feet atop the Big Hill. This grade offers sweeping vistas across the river canyon into the rugged mountains of Chihuahua, Mexico. From the summit, the road plunges down a steep, winding descent toward the lower river benches near Mile 46.5 (the route's low point at 2,293 feet) before leveling out as it approaches the western boundary of Lajitas.

Seasonal & Environmental Context

This is a deep Chihuahuan Desert corridor where environmental conditions dictate the ride:

Summer (May–September): Temperatures frequently exceed 100°F (38°C) by midday, with asphalt radiation making travel punishing. July through September brings the North American Monsoon, which can trigger severe flash floods. * Winter & Shoulder Seasons (October–April): Ideal daytime riding conditions with clear skies and temperatures in the 60s to 80s. However, winter mornings often start near freezing before rapid warming occurs. * Wind: High desert winds and sudden canyon gusts are common, particularly in late winter and spring, blowing fine sand across the road surface.

Logistics & Services

Fuel & Supplies: Fill up completely in Presidio or Lajitas. There are no gas stations, stores, or services of any kind along the nearly 50-mile stretch in between. * Connectivity: Cell phone service is non-existent throughout almost the entire state park corridor between the two towns. * Water: Carry adequate drinking water on the bike; desert dehydration happens rapidly even during short stops in dry, windy conditions.

Important Considerations

Debris in Low-Water Crossings: Rain miles away in the mountains can send water rushing through dry arroyos, leaving deep gravel, silt, and mud deposited across the pavement in low dips long after the water recedes. * Open Range & Wildlife: Much of this corridor is open range. Free-roaming cattle, burros, and native wildlife like javelina and desert mule deer frequently step into the roadway, especially around dawn and dusk. * Border Patrol Activity: Given the proximity to the international border, expect occasional U.S. Border Patrol vehicle traffic and fixed checkpoints east of Lajitas or north of Presidio.