U.S. Route 78 (US 78) is an east–west United States Numbered Highway that runs for 843.6 miles (1,357.6 km) from Swifton, Arkansas, to Charleston, South Carolina.

Around I-240, the road changes names to Lamar Avenue and then it meets US 51 and SR 3 before continuing southeastwardly to the Mississippi state line.

[1] In Memphis, US 78 is historically known as Pigeon Roost Road, and some aborted sections of the highway in Mississippi also claim that name as well as Lamar Avenue.

The highway runs across the northeastern rural part of the state, connecting several population centers.

After crossing Peachtree Street, where US 78 marks a boundary between downtown and Midtown, US 78 is largely conterminous with Ponce de Leon Avenue.

As it proceeds due east, this section of the route passes Ponce City Market and crosses the Eastside Trail of the BeltLine before skirting a number of Frederick Law Olmsted-designed parks in the Druid Hills Historic District at the eastern edge of the city.

After entering Decatur in DeKalb County, US 78 departs from Ponce de Leon Avenue to head northeast.

South of the site of North DeKalb Mall, another short freeway portion begins — leading from just inside the eastern rim of Interstate 285 (the Perimeter) to the suburbs of Clarkston, Tucker, Stone Mountain, and Snellville.

(From this point, Moina Michael Highway is signed as US 78 Business, which follows the original route of US 78 through Athens, Ga.) At the terminal eastern interchange of SR 316 both US 78 and US 29 turn right and join with SR 10 Loop, a mostly interstate-grade bypass that rings Athens-Clarke County.

From there US 78 passes through Oglethorpe, Wilkes, McDuffie and Columbia Counties into Augusta and then onto one of the twin bridges across the Savannah River into South Carolina.

Crossing Savannah River into the state, it goes northeast into Aiken before going southeasterly through the cities and towns of Williston, Blackville, Denmark, Bamberg, Branchville, and St. George.

The work includes expanding the road from four to six lanes, adding three new interchanges, and upgrading additional ones.