Interstate 37


Interstate 37 provides a link between San Antonio and Corpus Christi in South Texas. Like Interstate 45, IH 37 is entirely located within the Lone Star State. The freeway also provides part of through route to the Rio Grande Valley via connections with U.S. 281 / Interstate 69C and U.S. 77 / Interstate 69E. IH 37 is also one of the only limited-access routes available during a hurricane evacuation situation, being the main escape route from the South Texas coastline inland towards San Antonio and Austin.

Parallel U.S. Routes

Interstate 37 combines with U.S. 281 south from its independent freeway through north San Antonio to Downtown and Interstate 410 in southeast San Antonio. U.S. 281 shifts westward along IH 410 to its parallel alignment to IH 37 south to Leming and Pleasanton. The two come together again between Exits 103 and 72 near Three Rivers. U.S. 281 branches south from there toward Alice while the remainder of IH 37 mirrors the course of U.S. 181 southeast to Corpus Christi. U.S. 77 also briefly ties into Interstate 37 at Robstown and Interstate 69E.

Harbor Bridge

The new Harbor Bridge, an $899 million span planned to replace he 1950s-built bridge for U.S. 181 to the east, breaks ground on August 8, 2016.1 Four Proposed Build Alternatives were considered as of July 2013. The Red Alternative was ultimately chose. It ties in the new U.S. 181 bridge and alignment with the IH 37 interchange with the Crosstown Expressway (SH 286). Redesign of that exchange will replace the current design with a new directional T interchange with high speed flyovers between north-south U.S. 181 / SH 286 and IH 37 to the west. Connections with the IH 37 spur to the east will use the frontage roads in place of direct ramps.

An additional refinement considered for the bridge design is the elimination of the Staples Street overpass above Interstate 37 to the east of the Crosstown Expressway. An at-grade intersection between the two is proposed in place of the crossing. This effort is meant to make the Downtown area more pedestrian friendly.1 It would also in effect shorten Interstate 37 by at least 0.6 miles.


Interstate 37 was added to the original Interstate system in October 1957. It was included within the Texas Interstate Highway System by the Texas State Highway Commission in 1962 with 142 miles.2

The proposed section of Interstate 37 north of Downtown San Antonio to Interstate 410 was first planned as the North Expressway, a route connecting Downtown with the airport. Original plans called for the freeway to travel a straight line north from Downtown. However, local opposition arose due to the potential local impacts of the freeway. A lawsuit by the San Antonio Conservation Society resulted in an injunction preventing construction of the freeway as an Interstate in 1967.

Opposition to the freeway project remained through the late 1960s and early 1970s. The struggle reached a national audience when the freeway was profiled in Helen Leavitt's book Superhighway-Superhoax. With its proximity to or passage through parkland, a college campus, schools, residential areas and other sensitive areas, the route was changed to avoid these features. This helps explain the many curves of the freeway between Interstates 35 and 410. In 1973, the freeway was resurrected as a project to be built as U.S. 281 and without federal funds (and therefore not as part of IH 37). Construction ensued through the mid-1970s, and the Walter McAllister Expressway (U.S. 281) opened to traffic on February 7, 1978.3 The interchange offering direct connection ramps between U.S. 281 and Interstate 410 did not begin construction until 2006.

Highway Guides

Southern Terminus - U.S. 181 - Corpus Christi, Texas
Perspectives from Interstate 37
Texas Aquarium/U.S.S. Lexington button copy sign for the last exit of Interstate 37. This sign directs traffic to the U.S. 181/Texas 35 freeway. Texas 35 also takes traffic northward towards Ingleside and Aransas Pass in Patricio County. Photo taken by Jeff Royston (12/00).
Interstate 37 meets Milepost 0 in this southbound photograph. The southern terminus of Interstate 37 doubles as the southern terminus of U.S. 181 and Texas 35. The overlapped highways enter downtown Corpus Christi from the north via a crossing of Nueces Bay from Portland. Photo taken by Jeff Royston (12/00).
Traffic that does not exit onto U.S. 181/Texas 35 northbound towards Portland is directed onto Shoreline Boulevard towards the Corpus Christi Bayfront. The Interstate 37 freeway itself continues a short distance towards Bayfront Plaza before ending at surfaces streets. Photo taken by Mike Wiley (09/00).
Freeway ends one-quarter mile advisory sign on the Interstate 37 freeway southbound. This sign can be seen in the background of the above photograph. Traffic is reduced to 45 mph in anticipation of the transition to surface streets. Photo taken by Jeff Royston (12/01).
Reversing directions, the northern beginning of Interstate 37 and its associated milepost 0. The first exit Interstate 37 encounters is that of Exit 1C for Brownlee Boulevard and Port Avenue. The next interchange beyond is Exit 1C for the northern terminus of Texas 286, a freeway bisecting Corpus Christi to the south. Photo taken by Jeff Royston (12/01).
Perspective from U.S. 181 south
U.S. 181 and Texas 35 southbound conclude at the northbound beginning of Interstate 37. Three options are available to motorists at this location. The right-hand exit serves the Corpus Christi Port Area just northwest of this interchange. Mainline traffic transitions onto Interstate 37 northbound with connections to the Texas 286 Crosstown Expressway within one mile. Traffic wishing to access downtown departs on the left, connecting with a short one-quarter mile freeway stub of Interstate 37 to Shoreline Boulevard. Photo taken by Mike Wiley (09/00).
Perspective from Shoreline Boulevard
With the U.S. 181/Texas 35 Nueces Bay Bridge looming in the background, Shoreline Boulevard intersects with the northbound beginning of Interstate 37. Missing from this shield assembly is a sign for U.S. 181. The Interstate Highway 37 sign is an internally lit assembly. These are generally only found in urban locales. Photo taken by Jeff Royston (12/01).
A closer inspection of the Interstate 37 and Texas 35 shields Pictured in the above photograph. The terminus of Interstate 37 is a rare example where an Interstate, U.S., and State Route all conclude at the same location. Photo taken by Jeff Royston (12/01).
Perspective from Texas 286 north
Shifting focus to the north end of the Texas 286 Crosstown Expressway, the sign bridge displays Interstate 37 as only heading west of this point. In spite of this sign, Interstate 37 actually continues eastward for another one-half mile to (Exit 1A)/U.S. 181/Texas 35 north. Photo taken by Jeff Royston (12/00).
Detail of the guide signs at the northern terminus of Texas 286. San Antonio is a 138-mile drive to the northwest via Interstate 37. The freeway connects with U.S. 77 in 14 miles, the easternmost north-south thoroughfare in South Texas. Photo taken by Jeff Royston (12/00).
Approximately one year later, the same sign bridge on Texas 286 northbound at Interstate 37. The airport plate affixed to the left-hand panel relates to the Corpus Christi International Airport, situated two miles to the south of Interstate 37 Exit 5. Photo taken by Jeff Royston (12/01).
Northern Terminus - Interstate 35 - San Antonio, Texas
Perspective from Interstate 37 & U.S. 281 north
The first in a series of guide signs for the pending terminus with Interstate 35/Exits 142A-B posted along Interstate 37/U.S. 281 northbound. The last mainline exit of the Interstate departs to the right serving Commerce Street and downtown San Antonio. Photo taken 12/30/02.
Traffic from Commerce Street enters from the right as a second set of guide signs for Interstate 35 prepare motorists for the pending junction. Photo taken 12/30/02.
The speed limit drops to 50 mph on Interstate 37 as the freeway prepares to give way to U.S. 281 at Interstate 35. The US highway continues as a substandard freeway northward to Interstate 410 and Texas Loop 1604. The speed limit remains at 50 mph. Photo taken 12/30/02.
Three northbound lanes are maintained from Interstate 37 to the U.S. 281 freeway. Interstate 35 signage advises motorists that the right and left-hand lanes become exit-only. Photo taken 12/30/02.
The boxes below the signs are lane control signals that can be adjusted based on traffic conditions. These are posted on sign bridges throughout the metropolitan area of San Antonio. Photo taken 12/30/02.
Northbound Interstate 37/U.S. 281 at Exit 142A. Interstate 35 northbound travels 70 miles to the state capital of Texas, the city of Austin, from Interstate 37. Photo taken 12/30/02.
The final exit of Interstate 37 departs for Interstate 35 southbound. Between Interstates 10, 35, and 37, a loop of the downtown area is created. Interstate 35 travels 1.5 miles to Interstate 10 where it shares a three mile overlap west of downtown, before exiting the central business district en route to Laredo. Photo taken 12/30/02.
Although now past the Exit 142/Interstate 35 ramps, the final Interstate 37 milepost displays Mile 143, which is 0.06 of a mile prior to the official northern terminus mileage per the federal route log (143.06 miles). So here, Interstate 37 northbound ends, and U.S. 281 continues along freeway alignment for approximately six miles until reaching Interstate 410 and the San Antonio International Airport. Photo taken 12/30/02.
Perspective from Interstate 35 south
The first set of guide signs for Exits 158B/A of Interstate 37 south and U.S. 281 on Interstate 35 south. Interstate 35 has just left a brief overlap with Interstate 410 at this point. Photo taken 12/30/02.
The northern terminus of Interstate 37 occurs at Interstate 35's Exit 158. From the south, Interstate 37 is overlapped with U.S. 281 to the San Antonio Beltway (Interstate 410). To the north, U.S. 281 continues as a freeway from Interstate 35 to the C.W. Anderson Loop and ultimately towards Johnson City well north of the metropolitan area. This photo looks on Interstate 35 southbound, three-quarters of a mile from the junction with Interstate 37 south/U.S. 281. Photo taken 12/30/02.
Amassed within the 158th mile of Interstate 35 is a ramp to Texas Loop 368/Broadway. Exit 158C departs from Interstate 35 southbound for Texas Loop 368/North Alamo Street just before the conglomeration with Interstate 37 and U.S. 281. Photo taken 12/30/02.
Two lanes are allocated for Interstate 37/U.S. 281 southbound/Exit 158B from Interstate 35 south. The north-south freeway serves the eastern reaches of downtown, including the Alamodome sports/entertainment complex. Photo taken 12/30/02.
The interchange between Interstates 35 and 37 features mounds of concrete and stacked roadways. This photograph looks at the southbound ramp as it continues from the scene in the above photograph. Photo taken 12/30/02.
Descending underneath the Interstate 35 viaduct on the southbound ramp. The Interstate 35 and 37 junction is orientated more efficiently than the substandard interchanges of Interstate 10 at 37 or Interstate 10 at the south merge with Interstate 35. Photo taken 12/30/02.
Perspective from Interstates 10 west & 35 north
Interstate 35 northbound at the split with Interstate 10 west/Exit 156. A fascinating configuration of Interstate 10 begins at the split with Interstate 35 to Interstate 410 northwest of downtown. The highway is split between a four-lane lower deck (composed of the original freeway) that travels at ground level and an ultra-modern split viaduct that soars above. The left-hand lanes take Interstate 35 as it encircle downtown to the north. A split viaduct configuration also is in place for Interstate 35. Ramps to Interstate 37 and U.S. 281 depart in two miles. Photos taken 12/30/02.
Continuing beyond the split with Interstate 10 on Interstate 35 northbound. Pictured here is the partition of Interstate 35 into its decked components. All traffic interests to Interstate 37 and U.S. 281 are advised to use the upper deck to access those routes. Photo taken by Chris Patriarca (06/24/03).
Interstate 35 northbound on the lower deck at Exit 157C/Saint Mary's Street. Access is available to Exit 158 on the lower carriageway of Interstate 35 as this overhead guide sign suggests. Photo taken by Chris Patriarca (06/24/03).
Interstate 35 northbound ascends and the two decks reunite just in time to encounter the Interstate 37/U.S. 281 stack interchange of Exit 158. A pair of lanes are allocated for the north-south freeway. Traffic from the upper deck is already in place for these ramps. Traffic from the lower deck must contend with weaving traffic to utilize the same ramps. Photo taken by Chris Patriarca (06/24/03).
Three northbound lanes of Interstate 35 punch through the Exit 158 interchange. To the right the two exit-only lanes prepare to split into their respective directions for Interstate 37 south and U.S. 281. Photo taken by Chris Patriarca (06/24/03).
Interstate 35 continues eastward beyond the gore point of Exit 158. The overheads here display the formal name of the U.S. 281 freeway north of Interstate 37, that of the McAllister Freeway. Also featured is the connection to Texas Loop 368/Broadway via the U.S. 281 northbound ramp. This state route represents the original U.S. 81 routing through northeast San Antonio. Photo taken by Chris Patriarca (06/24/03).


  1. "Harbor Bridge open house to show possible bridge modifications." Corpus Christi Caller Times, June 23, 2016.
  2. From Anywhere to Everywhere: The Development of the Interstate Highway System in Texas by Penny Beaumont, Rhonda Brinkmann, David Ellis, Chris Pourteau, and Brandon V. Webb, Texas Transportation Institute, page 29.
  3. From Anywhere to Everywhere: The Development of the Interstate Highway System in Texas by Penny Beaumont, Rhonda Brinkmann, David Ellis, Chris Pourteau, and Brandon V. Webb, Texas Transportation Institute, page 24.

Page Updated June 24, 2016.

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State Texas
Mileage 143.00
Cities Corpus Christi, Mathis
Junctions I=410, I=10, I=35
Source: December 31, 2016 Interstate Route Log and Finders List
Interstate 37 was 44% complete in 1972
Interstate 37 was completed from San Antonio south to FM 1303 (where Loop 1604 crosses IH 37 now) by 1972 and from Corpus Christi north to FM 534 at Swinney Switch.