Since widening was completed in 2008, a portion of the highway west of Houston is now also believed to be the widest in the world, at 26 lanes when including feeders.

El Paso, near the New Mexico state line, is 785 mi (1,263 km) from the western terminus of I-10 in Santa Monica, California, making it closer to Los Angeles than it is to Orange, Texas, 857 mi (1,379 km) away at the Louisiana state line.

I-10 enters Texas northwest of El Paso near Anthony and runs southward, alongside US Route 85 (US 85) and US 180.

As of the summer of 2016, the stretch of I-10 that runs through El Paso was in the midst of a major construction project, which sought to link North/South Desert Boulevard (the westside frontage roads) with Gateway East and Gateway West (the central and eastside frontage roads).

Gateway East Boulevard is the longest, extending continuously for roughly 22 mi (35 km).

Continuing towards Tornillo and Fabens, I-10 turns to the southeast and runs alongside the Rio Grande and the Mexican border for approximately 60 mi (97 km).

Because I-10 crosses some of the most rural and sparsely inhabited parts of the United States, notably the Trans-Pecos Region, it has several unique features that differentiate it from other interstate highways.

The section of I-10 from Ralph Fair Road (FM 3351) to La Cantera Parkway includes HOV lanes for both directions.

It was necessary to design the freeway this way in order to accommodate the amount of traffic heading into downtown and to fit into the narrow corridor that was surrounded by existing infrastructure.

A project completed in 2014 added one extra auxiliary lane in each direction between Shepherd Drive and Taylor Street.

[citation needed] In addition, the eastbound feeder road that ends at Studemont was extended to Taylor Street.

I-10 meets US 90 again near the recently reconstructed Purple Heart Memorial Bridge over the Neches River; these highways travel concurrently the remainder of the way across the state.

I-10 replaced and runs concurrently with US 85 from the New Mexico state line up until the two diverge at mile marker 13.

The two highways parallel each other for several miles until US 85 continues to head south to the border with Mexico and I-10 turns east towards Downtown El Paso.

Prior to the Interstate Highway system, US 85 ran concurrent with US 80 from the New Mexico border until the two diverged in Downtown El Paso.

When I-10 was constructed in downtown El Paso, several blocks were demolished, and a sub-grade trench was built for the freeway.

The section from Culebra Road to Woodlawn Avenue opened as the first freeway in San Antonio in 1949, but was signed as US 87.

The $11 million project to construct the interchange with I-37 was at the time the largest single contract in the history of the state highway commission.

Rapid growth in San Antonio led to the original highway quickly becoming inadequate, with the result that it has been in perpetual construction and expansion.

In the 1980s, the portion just northwest of downtown was reconstructed to add a double deck feature to expand the freeway to five lanes in each direction.

[19] In 2000, increased traffic levels and congestion led to plans being approved for widening of the freeway to 16 lanes with a capacity for 200,000 cars per day.

[20] Two intersections were rebuilt (Beltway 8 and I-610), toll booths were added, together with landscaping as part of Houston's Highway Beautification Project.

Tolls on the managed lanes vary by vehicle occupancy, axle count and time of day.

Days of continuous heavy rains, coupled with the controversial opening of the Toledo Bend Dam and the release of 207,000 to 208,000 cu ft/s (5,900 to 5,900 m3/s) into the river, caused the closing of I-10.

[citation needed] In 2020, I-10 between Beaumont and the Louisiana state line was shut down due to debris and heavy rain caused by Hurricanes Delta and Laura.