List of highways numbered 51
The following highways are numbered 51:
Australia
- Kamilaroi Highway
- Plenty Road
Cambodia
- National Road 51
Canada
- Alberta Highway 51
- Saskatchewan Highway 51
Cuba
- Caimito–Salado Road
Finland
- Finnish national road 51
France
- A51 autoroute
Greece
- EO51 road
Hungary
- M51 expressway
India
- National Highway 51
Iran
- Zobahan Freeway
- Road 51
Italy
- Autostrada A51
Japan
- Japan National Route 51
South Korea
Lebanon
- 51M Coastal Highway
New Zealand
- New Zealand State Highway 51
Philippines
- N51 highway
South Africa
- R51
Turkey
- , a motorway in Turkey running from Adana to Mersin.
United Kingdom
- British A51
United States
- U.S. Route 51
- Alabama State Route 51
- Arizona State Route 51
- Arkansas Highway 51
- California State Route 51
- Colorado State Highway 51
- Florida State Road 51
- * County Road 51
- Georgia State Route 51
- * Georgia State Route 51
- Hawaii Route 51
- Idaho State Highway 51
- Illinois Route 51
- Indiana State Road 51
- Iowa Highway 51
- K-51
- Maryland Route 51
- *Maryland Route 51A
- *Maryland Route 51B
- *Maryland Route 51C
- *Maryland Route 51D
- *Maryland Route 51E
- *Maryland Route 51F
- M-51
- Minnesota State Highway 51
- * County Road 51
- * County Road 51
- Missouri Route 51
- Nebraska Highway 51
- * Nebraska Link 51A
- * Nebraska Link 51B
- * Nebraska Link 51C
- * Nebraska Recreation Road 51E
- * Nebraska Recreation Road 51F
- * Nebraska Recreation Road 51G
- * Nebraska Recreation Road 51H
- Nevada State Route 51
- New Hampshire Route 51
- New Jersey Route 51
- * County Route 51
- ** County Route S51
- * County Route 51
- New Mexico State Road 51
- New York State Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- * County Route 51
- North Carolina Highway 51
- Ohio State Route 51
- Oklahoma State Highway 51
- * Oklahoma State Highway 51A
- * Oklahoma State Highway 51B
- Oregon Route 51
- Pennsylvania Route 51
- Rhode Island Route 51
- South Carolina Highway 51
- Tennessee State Route 51
- Texas State Highway 51
- * Texas State Highway Spur 51
- * Farm to Market Road 51
- * Texas Park Road 51
- Utah State Route 51
- Virginia State Route 51
- * Virginia State Route 51
- West Virginia Route 51
- * West Virginia Route 51
- * West Virginia Route 51
- Wisconsin Highway 51
- Wyoming Highway 51
Vietnam
- National Road 51