State Route 21 (SR 21) is an 84.4-mile-long (135.8 km) state highway that travels southeast-to-northwest through portions of Chatham, Effingham, Screven, and Jenkins counties in the eastern part of the U.S. state of Georgia. The highway connects the Savannah and Millen areas, via Garden City, Port Wentworth, Rincon, Springfield, and Sylvania. SR 21 formerly had its northern terminus at the South Carolina state line in Augusta. It traveled on the current path of US 25/SR 121 from Millen to Augusta. In the city, it used the path of SR 28 (Broad Street) and the Georgia segment of US 25 Bus.