SH 77 is 46.815 miles (75.341 km) long, and connects U.S. Highway 259 (US 259) to the Louisiana state line.

After cutting across the south side of Atlanta, where it meets US 59, SH 77 cuts to the southeast, and crosses into the very northwest corner of Louisiana near Three Corners (where Arkansas, Louisiana and Texas meet), becoming Louisiana Highway 1.

On March 11, 1935, SH 77 Spur was designated to Marietta.

This would be cancelled on completion, but would be restored on April 19, 1937, as SH 245.

On July 15, 1935, the section of SH 77 west of Naples was cancelled.