List of highways numbered 421

The following highways are numbered 421:

Canada

 * Manitoba Provincial Road 421
 * Newfoundland and Labrador Route 421

Japan

 * Japanese National Route Sign 0421.svg Japan National Route 421

United States

 * US 421.svg U.S. Route 421
 * Florida 421.svg Florida State Road 421
 * Volusia County 421.svg County Road 421 (Volusia County, Florida)
 * Georgia 421.svg Georgia State Route 421 (unsigned designation for Interstate 516)
 * New Mexico 421.svg New Mexico State Road 421
 * NY-421.svg New York State Route 421
 * OH-421.svg Ohio State Route 421
 * Ellipse sign 421.svg Puerto Rico Highway 421
 * South Carolina 421.svg South Carolina Highway 421
 * Secondary Tennessee 421.svg Tennessee State Route 421
 * Texas Spur 421.svg Texas State Highway Spur 421