List of highways numbered 21
For roads named A21 see ; List of A21 roads
Route 21, or Highway 21, can refer to:
International
- European route E21
Australia
- Chandler Highway
- Toowoomba Connection Road
- – Kakadu 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
Cuba
- Highway 6–21
- Highway 4–21
Czech Republic
- I/21 Highway; Czech: Silnice I/21
Greece
- EO21 road
Hungary
- Main road 21
India
- National Highway 21
Iran
- Road 21
Ireland
- N21 road
Italy
- Autostrada A21
Japan
- Japan National Route 21
Korea, South
- National Route 21
Moldova
- M21 highway
New Zealand
- New Zealand State Highway 21
Paraguay
- Image:R21-PY.svg|20px| National Route 21
Turkey
- , a motorway in Turkey running from Kemerhisar, Niğde Province to Tarsus, Mersin Province.
United Kingdom
- British A21
- A21 road
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