The following highways are numbered 421:

This list is incomplete; you can help by adding missing items. (August 2008)

Canada

• Manitoba Provincial Road 421
• Newfoundland and Labrador Route 421

Japan

• Japan National Route 421

United States

• U.S. Route 421
• Florida State Road 421
  • County Road 421 (Volusia County, Florida)
• Georgia State Route 421 ( unsigned designation for Interstate 516)
• New Mexico State Road 421
• New York State Route 421
• Ohio State Route 421
• Puerto Rico Highway 421
• South Carolina Highway 421
• Tennessee State Route 421
• Texas State Highway Spur 421

This article includes a list of roads, streets, highways, or other routes that are associated with the same title.
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