List of highways numbered 21

International

• European route E21

  Australia

• Chandler Highway

  Austria

• Wiener Außenring Autobahn

  Cambodia

• National Road 21

  Canada

• Alberta Highway 21
• British Columbia Highway 21
• Manitoba Highway 21
• Newfoundland and Labrador Route 21
• Ontario Highway 21
• Prince Edward Island Route 21
• Saskatchewan Highway 21

  Costa Rica

• National Route 21

  Czech Republic

• I/21 Highway; Czech: :cz:Silnice I/21|Silnice I/21

  Hungary

• Main road 21

  India

• National Highway 21

  Iran

• Road 21

  Japan

• Japan National Route 21

  Korea, South

• National Route 21

  New Zealand

• New Zealand State Highway 21

  Turkey

• , a motorway in Turkey running from Kemerhisar, Niğde Province to Tarsus, Mersin Province.

  United Kingdom

• British A21

  United States

• U.S. Route 21
• Alabama State Route 21
• Arkansas Highway 21
• * Arkansas Highway 21E
• * Arkansas Highway 21W
• California State Route 21
• * County Route A21
• * County Route E21
• * County Route G21
• * County Route J21
• * County Route S21
• Colorado State Highway 21
• Connecticut Route 21
• Florida State Road 21
• * County Road 21B
• * County Road 21B
• * County Road 21D
• * County Road 21
• * County Road 21
• Georgia State Route 21
• Hawaii Route 21
• Idaho State Highway 21
• Illinois Route 21
• Indiana State Road 21
• Iowa Highway 21
• Kentucky Route 21
• Louisiana Highway 21
• Maryland Route 21
• Massachusetts Route 21
• M-21
• Minnesota State Highway 21
• * County Road 21
• * County Road 21
• * County Road 21
• Mississippi Highway 21
• Missouri Route 21
• Montana Highway 21
• Nebraska Highway 21
• * Nebraska Spur 21B
• * Nebraska Spur 21C
• Nevada State Route 21
• New Jersey Route 21
• * County Route C21
• * County Route 21
• New Mexico State Road 21
• New York State Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• ** County Route 21B
• ** County Route 21C
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• North Carolina Highway 21
• North Dakota Highway 21
• Ohio State Route 21
• Pennsylvania Route 21
• South Carolina Highway 21
• South Dakota Highway 21
• Tennessee State Route 21
• Texas State Highway 21
• * Texas State Highway Loop 21
• * Farm to Market Road 21
• * Texas Park Road 21
• Utah State Route 21
• State Route 21
• Washington State Route 21
• * Primary State Highway 21
• * Secondary State Highway 21B
• * Secondary State Highway 21C
• County Route 21
• * County Route 21
• * County Route 21
• * County Route 21
• Wisconsin Highway 21

• Puerto Rico Highway 21