U.S. Route 77 (US 77) is a part of the United States Numbered Highway System that runs from the Veteran's International Bridge in Brownsville to Sioux City, Iowa. In Texas, the road runs south-north for 471.3 miles (758.5 km) from the International border to the Oklahoma state line north of Gainesville. The highway is being upgraded to a freeway near Corpus Christi to connect to the freeway part of the highway in Raymondville as part of future I-69. A freeway in Robstown is already signed as part of I-69. From Waco to the Oklahoma state line, US 77 overlaps or runs parallel to I-35/I-35E.

US 77 crosses the Rio Grande River with US 83 on the Veteran's International Bridge. The two highways run together until Harlingen. US 83 runs west (north) to McAllen while US 77 runs north to Raymondsville. The highway is only one to pass through Kenedy County.

In Robstown, US 77 picks up the I-69 designation until the interchange with I-37 in north Corpus Christi. US 77 shares a short overlap with I-37 before leaving the highway. US 77 runs through many small to mid-size communities before arriving in Waco. Here, US 77 begans its overlap with I-35 that last until Hillsboro, where the highway then parallels I-35E until Red Oak.

US 77 has a unsigned overlap with I-35E until US 77 leaves the interstate in Corinth to serve Denton. The highway then returns to I-35 in north Denton until the two highways cross into Oklahoma together north of Gainesville.