Interstate 37 (I-37): Corpus Christi to San Antonio Route and Safety Data

How long is I-37?

I-37 runs 143.15 miles in the January 2026 FHWA Route Log, all in Texas, and Interstate Guide lists the same length. Wikipedia's infobox shows 143.00 miles and notes that the route officially begins at the gore point of the ramps at its Corpus Christi end.

The Route Log books none of I-37's pavement to another Interstate, so the crash rate below uses the full 143.15 miles with no overlap adjustment. US highways do share the road for long stretches. US 77 rides along for a short way across the Nueces River in Corpus Christi, US 281 joins between Three Rivers and the Pleasanton exit, and US 281 comes back on from I-410 into downtown San Antonio. Those shared miles stay with I-37.

Where I-37 starts and ends

I-37 begins in Corpus Christi at US 181 and SH 35, close to downtown and the Port of Corpus Christi. From there US 181 carries traffic on toward the Harbor Bridge over the Corpus Christi Channel. The northern end is at I-35 on the northeast side of downtown San Antonio, exits 142A and 142B, and the freeway keeps going north as US 281, the McAllister Freeway.

Heading north, I-37 passes the SH 286 and SH 358 interchanges, serves Corpus Christi International Airport and crosses the Nueces River. It runs by Mathis and Lake Corpus Christi, passes near George West, and picks up US 281 near Three Rivers and Choke Canyon Reservoir. The route also serves Oakville, Campbellton and Whitsett. Near the north end it bypasses Pleasanton to the east and reaches San Antonio by way of Elmendorf.

Interstate junctions along I-37

Read from south to north, the list is short. In Corpus Christi I-37 meets I-69E, which arrives with US 77 at exit 14A; Wikipedia gives that interchange as the current northern end of I-69E. Nothing else from the Interstate list crosses I-37 until San Antonio, where it meets I-10 at a stack interchange on the southeast corner of downtown and then ends at I-35.

Two large interchanges are left off the list. US 59 meets I-37 at exit 56 east of George West, on a corridor planned to become I-69W. The I-410 loop around San Antonio crosses at exit 133, but it is a three-digit route.

Fatal crashes on I-37

FARS records 68 fatal crashes on I-37 from 2020 to 2024, and they killed 81 people, about 16 a year. Over the route's 143.15 miles that comes to 11.3 deaths per 100 miles each year, above the Interstate average of 9.5. I-37 ranks 15th of the 56 routes we rate, where 1st has the highest rate. The yearly count swung widely: 9 deaths in 2020, 19 in 2021, a peak of 23 in 2022, then 13 in 2023 and 17 in 2024.

All 81 deaths fall in the five counties the road crosses. Bexar County, the San Antonio end, had 28, about a third of the total. The three counties in between added up to more than the two city counties together: Atascosa had 17, Live Oak 15 and San Patricio 11, against 10 in Nueces County, which holds Corpus Christi.

Counties with the most I-37 crash deaths

Bridges on I-37

The 2025 National Bridge Inventory lists 181 bridges carrying I-37's main line, and none of them rate Poor. Of the rest, 96 rate Good and 85 rate Fair. The median bridge on the route was built in 1972.

Some spans are much older than that. Wikipedia dates the southbound Nueces River bridge in Corpus Christi to 1933, when it was built for US 77, and the northbound bridge to 1958, when US 77 was widened to four lanes. Just past the south end, US 181 crosses the Corpus Christi Channel on the Harbor Bridge, and Interstate Guide puts the cost of replacing that 1959 span at $802.9 million, with ground broken on August 8, 2016. Wikipedia's exit list shows the connections from I-37 to northbound US 181 and SH 35 opening in June 2025 for southbound traffic and in September 2025 for northbound traffic.

Tolls on I-37

FHWA's toll inventory as of January 1, 2023 lists no facilities on I-37, so a trip from Corpus Christi to San Antonio costs nothing in tolls. We checked Wikipedia, Interstate Guide and TxDOT's current San Antonio project page and found no express or toll lanes added to I-37 since then.

Building I-37, from the 1957 plan to 1981

Interstate Guide says the route was added to the Interstate system in October 1957, and the state highway commission put it in the Texas system at 142 miles in 1962. Wikipedia dates the I-37 designation to October 16, 1959. The first pieces to open were at the two ends: Corpus Christi sections, including the SH 286 interchange, in 1963, and the first San Antonio sections in 1967.

San Antonio's part was finished in 1972, including the I-35 interchange downtown. That year, by Interstate Guide's count, the route was 44 percent complete, open from San Antonio south to FM 1303 and from Corpus Christi north to FM 534 at Swinney Switch. The rural middle filled in from 1975 on in Live Oak and Atascosa counties, and Wikipedia counts the route complete in 1981, when the SH 72 interchange near Three Rivers and the last bridges in the Pleasanton area were done.

The freeway north of downtown San Antonio took a different path. Interstate Guide says a 1967 lawsuit by the San Antonio Conservation Society blocked building the North Expressway as an Interstate. The road was revived in 1973 without federal money and opened as US 281, the McAllister Expressway, on February 7, 1978. Inside San Antonio, I-37 carries two names honoring World War II Medal of Honor recipients: the Lucian Adams Freeway from I-410 to I-10 and the William J. Bordelon Freeway from I-10 to I-35.

The newest work is on the South Side. TxDOT plans to convert the I-37 interchange at Loop 13 (SE Military) into a diverging diamond, with a bypass ramp above it and 10-foot shared-use paths in both directions. The $40 million project covers nearly 2 miles up to I-410 with construction set to begin in fall 2026 and finish in 2029.

I-37 traffic and road conditions

Since I-37 stays in Texas, DriveTexas is the one traveler site that covers all of it. Look there for closures during a coastal hurricane evacuation, and for the weeknight lane closures, mostly 9 p.m. to 5 a.m., that TxDOT plans during the Loop 13 interchange work in San Antonio.

I-37 questions