U.S. Route 77 is a north–south United States highway. It is unsigned in and around Dallas, Texas. Its historic segment through South Dakota and Minnesota was decommissioned with the advent of Interstate 29 but otherwise the route has been spared the decommissioning that has shortened other US highways. The route has major freeway sections in Oklahoma City including the Broadway Extension connecting suburban Edmond to downtown Oklahoma City.

As of 2005, the highway's northern terminus is in Sioux City, Iowa at an interchange with Interstate 29. Its southern terminus is in Brownsville, Texas, at Veteran's International Bridge on the U.S.-Mexico border, where it connects with Mexican Federal Highway 180.

The section between the Oklahoma-Texas state line and Waco, Texas is mostly co-located with Interstate 35 and the 35E spur through Dallas, Texas and, where it is co-located, it is not signed.

The two stretches in Texas that are not co-located are a stretch wholly within the city of Denton and a longer stretch from near Red Oak, to Hillsboro, the reason being that US 77 is a separate road between the two, serving the town of Waxahachie.

As of 2004, US 77 Alternate has a northern terminus in Hallettsville, Texas. It rejoins US 77 at Refugio, Texas. While the main line of US 77 passes through Victoria, Alternate US 77 veers to the west to serve Yoakum and Cuero.

The southern end extends from I-37 near Corpus Christi to Harlingen, where it merges with U.S. Highway 83 and runs through the cities of Harlingen, San Benito and Brownsville to its southern terminus at the United States/Mexico border.

A section of U.S. 77 located in the Giddings, Texas area is known as the Martin Luther King Jr. Memorial Highway.

Another section of US 77, from I-37 to SH 44 in Nueces County, was redesignated I-69/US 77 in 2011.

In Oklahoma, U.S. Route 77 runs north–south, paralleling Interstate 35, connecting Texas to Kansas and running for 268 miles (431 km) through the central part of the state. It passes through many major cities, including Ardmore, Oklahoma City and Norman, Guthrie, and Ponca City. It has a freeway section, the Broadway Extension, connecting to Edmond, in addition to sections that are co-flagged with Interstate-35, and Interstate-235.

US-77 runs for 234 miles (377 km) in Kansas. Between the U.S. 40 junction and the Cowley County line is designated as a Blue Star Memorial Highway. In Cowley County, it is the Robert B. Docking Memorial Highway. Near Arkansas City it is the Walnut Valley Greenway.

From Nebraska to U.S. 24 and from K-15 to Arkansas City, it is part of the National Highway System.

In Nebraska, U.S. 77 is a major north–south artery connecting the capital city of Lincoln with outlying areas to the north and south. The highway is designated as the Homestead Expressway from Beatrice to Interstate 80 at Lincoln. North of Interstate 80, U.S. 77 continues as an expressway to Wahoo, where it becomes a two-lane undivided road. It remains a two-lane highway except for two sections near Fremont, which are four-lane divided highways. The expressway north of Fremont is shared with U.S. Route 275 and Nebraska Highway 91. U.S. 275 and NE 91 separate from U.S. 77 just south of Winslow, Nebraska and U.S. 77 continues north as a two-lane highway until it meets U.S. Route 75 at Winnebago. The two highways run together to the junction of Interstate 129 and U.S. Route 20 at Dakota City, where U.S. 75 breaks off and U.S. 77 continues northward as a divided highway through South Sioux City before exiting the state via the Siouxland Veterans Memorial Bridge.

U.S. Route 77 barely enters Iowa. After crossing the Missouri River at Sioux City, the highway ends at the volleyball interchange with Interstate 29. Its total length in Iowa is slightly more than 0.4 miles (0.64 km).

U.S. 77 previously extended north through South Dakota to Ortonville, Minnesota. It followed the current Interstate 29 corridor up to the Toronto, South Dakota area, and then followed current South Dakota Highway 15 north to Milbank, South Dakota. After reaching Milbank, it went east in a concurrency with U.S. Route 12 to Ortonville, where it ended at U.S. Route 75. Portions of the old highway in the Sioux Falls area exist today as South Dakota Highway 115.