List of highways numbered 321
The following highways are numbered 321:
Canada
- Nova Scotia Route 321
- Saskatchewan Highway 321
China
- China National Highway 321
Costa Rica
- National Route 321
Cuba
- Cuatro Caminos–Arroyo de Agua Road
- Las Minas–Comunidad Pedro Pi Road
- Santa Clara–Caibarién Road
Japan
- Japan National Route 321
United States
- U.S. Highway 321
- Arkansas Highway 321
- * Arkansas Highway 321 Spur
- Georgia State Route 321
- Kentucky Route 321
- Louisiana Highway 321
- Mississippi Highway 321
- Nevada State Route 321
- New Mexico State Road 321
- New York:
- * New York State Route 321
- * County Route 321
- North Carolina Highway 321
- Ohio State Route 321
- Pennsylvania Route 321
- Puerto Rico Highway 321
- Tennessee State Route 321
- Texas:
- * Texas State Highway 321
- * Texas State Highway Loop 321
- * Farm to Market Road 321
- Virginia State Route 321
- * Virginia State Route 321
- Wyoming Highway 321