The bridge was placed on the
National Register of Historic Places in 1996. For whatever reason, while just about all of the bridge is within Oklahoma's boundaries, the National Register lists it on the Texas side, in Fannin County. Some maps are on the arbitrary side, too, placing the border in the middle of the Red River, while the actuality is that Oklahoma pretty much extends across all of the river. The National Register's Registration Form (see link, above) provides some good reading, noting later in the document the contentious history that Texas and Oklahoma have had regarding bridges (slight edits):
"The State Highway 78 Bridge at the Red River consists of eight riveted K-truss through spans, with two camelback pony truss spans at each end. With an overall length of 2,108 feet, the bridge provides a crossing over the Red River between Fannin County. Texas, and Bryan County, Oklahoma, on State Highway (SH) 78. SH 78 is a short route of about 85 miles that originally extended from Garland, a suburb of Dallas, to Bonham, the Fannin County seat. By 1933, the route was extended north into Oklahoma. The Red River bridge links Bonham in Fannin County with Durant in Bryan County. Hugging the northern edge of the Blackland Prairie region of North Texas, Fannin County has an economy based primarily on agriculture, with cotton and grains the principle crops.
The Texas Highway Department (THD) and the Oklahoma Highway Commission (OHC) jointly undertook the construction of the Red River bridge. OHC bridge engineers, who were primarily responsible for designing the bridge, chose K-trusses for the main spans and camelback pony trusses for the approach spans. Two rows of 4-inch deep steel angle members form the truss railing. The truss spans rest on reinforced concrete piers with straight cylindrical columns in a dumbbell configuration. Concrete abutments support the bridge ends. The bridge's south abutment and all piers use concrete footings; the north abutment is supported on reinforced concrete foundation piling. A Texas-shaped state boundary marker at the bridge entrance marks the interstate crossing. A bronze plaque affixed to a concrete monument identifies the bridge contractor, as well as the government agencies involved in the project. The plaque reads:
RED RIVER BRIDGE
BUILT IN 1938 BY THE
TEXAS HIGHWAY DEPARTMENT
AND THE
OKLAHOMA HIGHWAY COMMISSION
- * -
UNITED STATES
BUREAU OF PUBLIC ROADS
-* -
TEXAS HIGHWAY COMMISSION
ROBERT LEE BOBBITT CHAIRMAN
JOHN WOOD MEMBER
HARRY HINES MEMBER
JULIAN MONTGOMERY
HIGHWAY ENGINEER
KANSAS CITY BRIDGE CO.
CONTRACTORS
Roadside parks, one on each side of the approach roadway, overlook the river's south bank."
While the color of the soil of the Red River gives the river its name, those who venture down to the river banks will encounter black soil, or worse, very slippery mud. You're in the Blackland Prairie. It is not an easy task to get down below, but one of the two roadside parks (on the southwest side) has a place where someone has attached a cable to assist in scaling the bluff. Be very, very careful, as the steep slopes and the mud below can be a challenge. The smell of the water should be sufficient to deter you from going into it, as you never know what kinds of bacteria are floating around these days. Best of luck driving to the park on the southeast side, and access on the Oklahoma side appears to be very limited. You'll find the park on the southwest side to be filled with trash, and it can be cramped: It might be best to park on the road before it descends the bluff.
Upon entering Texas, you will be greeted by the Texas-shaped boundary marker referenced in the Registration Form, and a green "Welcome to Texas" sign. However, there is no such greeting over on the Oklahoma side. Acknowledgement that you're in Oklahoma takes the form of a Highway 78 sign with the Oklahoma silhouette. Just to the north is Yuba, OK, but you won't see any welcome signs.
This highway can see heavy traffic. The best you might be able to do is slow down to get photos as you cross, but use your head and don't let that semi going 55 mph barrel down on you. Don't get out of your car! It's much safer to park and take photos where the bridge begins.
There are a few small stores on both sides of the river, but if you're looking for facilities, you're going to be driving for some time.