Alabama State Route 21

State Route 21
State Route 21
Route information
	Maintained by ALDOT
Length	279.471 mi (449.765 km)
Major junctions
South end	SR 97 at the Florida state line in Atmore
	US 31 in Atmore and Montgomery; I-65 near Atmore and Montgomery; US 84 in Monroeville; US 80 in Lowndes County; US 82 in Montgomery; I-85 in Montgomery; US 280 in Sylacauga; I-20 in Oxford; US 78 in Oxford; US 431 in Anniston;
North end	US 278 at Piedmont
Location
Country	United States
State	Alabama
Counties	Escambia, Monroe, Wilcox, Lowndes, Montgomery, Elmore, Coosa, Talladega, Calhoun
Highway system
	Alabama State Highway System; Interstate; US; State;

State Route 21 (SR 21) is a 279-mile (449 km) state highway that extends from the Florida state line, near Atmore in Escambia County to Piedmont in Calhoun County. The route travels almost the entire length of the state from the northeast to the southwest. It is the longest signed state route in Alabama.