For roads named A21 see ; List of A21 roads
Route 21, or Highway 21, can refer to:
International
E21 European route E21
Australia
Chandler Highway
Toowoomba Connection Road (QLD)
- Kakadu Highway
Toowoomba Connection Road (QLD)
- Austria
Wiener Außenring Autobahn
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Cambodia
- National Road 21 (Cambodia)
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
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Costa Rica
National Route 21
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Czech Republic
I/21 Highway; Czech: Silnice I/21
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Hungary
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Main road 21 (Hungary)
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India
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21
National Highway 21 (India)
Iran
Road 21
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Japan
Japan National Route 21
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Korea, South
National Route 21
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New Zealand
New Zealand State Highway 21
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Turkey
O-21, a motorway in Turkey running from Kemerhisar, Niğde Province to Tarsus, Mersin Province.
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United Kingdom
British A21 (Hastings-London)
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United States
U.S. Route 21
Alabama State Route 21
Arkansas Highway 21 
Arkansas Highway 21E (former)
Arkansas Highway 21W (former)
California State Route 21 (former) 
County Route A21 (California)
County Route E21 (California)
County Route G21 (California)
County Route J21 (California)
County Route S21 (California)
Colorado State Highway 21
Connecticut Route 21
Florida State Road 21 
County Road 21B (Clay County, Florida)
County Road 21B (Duval County, Florida)
County Road 21D (Duval County, Florida)
County Road 21 (Marion County, Florida)
County Road 21 (Putnam County, Florida)
Georgia State Route 21
Hawaii Route 21 (former)
Idaho State Highway 21
Illinois Route 21
Indiana State Road 21 (former)
Iowa Highway 21
Kentucky Route 21
Louisiana Highway 21
Maryland Route 21
Massachusetts Route 21
M-21 (Michigan highway)
Minnesota State Highway 21 
County Road 21 (Anoka County, Minnesota)
County Road 21 (Hennepin County, Minnesota)- County Road 21 (Scott County, Minnesota)
- Mississippi Highway 21
Missouri Route 21
Montana Highway 21
Nebraska Highway 21 
Nebraska Spur 21B
Nebraska Spur 21C
Nevada State Route 21 (former)- New Jersey Route 21
County Route C21 (Bergen County, New Jersey)
County Route 21 (Monmouth County, New Jersey)
New Mexico State Road 21
New York State Route 21 - County Route 21 (Allegany County, New York)
- County Route 21 (Chautauqua County, New York)
- County Route 21 (Columbia County, New York)
- County Route 21B (Columbia County, New York)
County Route 21C (Columbia County, New York)
- County Route 21 (Delaware County, New York)
County Route 21 (Dutchess County, New York)
County Route 21 (Erie County, New York)
County Route 21 (Essex County, New York)- County Route 21 (Genesee County, New York)
County Route 21 (Hamilton County, New York)- County Route 21 (Herkimer County, New York)
County Route 21 (Lewis County, New York)- County Route 21 (Oneida County, New York)
- County Route 21 (Ontario County, New York)
- County Route 21 (Orange County, New York)
- County Route 21 (Oswego County, New York)
- County Route 21 (Otsego County, New York)
- County Route 21 (Putnam County, New York)
County Route 21 (Rensselaer County, New York)
County Route 21 (Saratoga County, New York)- County Route 21 (Schoharie County, New York)
County Route 21 (Suffolk County, New York)
County Route 21 (Sullivan County, New York)- County Route 21 (Ulster County, New York)
County Route 21 (Washington County, New York)- County Route 21 (Westchester County, New York)
- County Route 21 (Wyoming County, New York)
County Route 21 (Yates County, New York)
North Carolina Highway 21 (former).svg.png)
North Dakota Highway 21
Ohio State Route 21
Pennsylvania Route 21.svg.png)
South Carolina Highway 21 (1920s) (former)
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 (Virginia 1918-1933) (former)
Washington State Route 21 
Primary State Highway 21 (Washington) (former)
Secondary State Highway 21B (Washington) (former)
Secondary State Highway 21C (Washington) (former)
- County Route 21 (Jackson County, West Virginia)
- County Route 21 (Kanawha County, West Virginia)
- County Route 21 (Wirt County, West Virginia)
- County Route 21 (Wood County, West Virginia)
Wisconsin Highway 21
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- Territories
Puerto Rico Highway 21
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See also
- List of A21 roads
- List of highways numbered 21A
| Previous | Lists of highways | Next |
|---|---|---|
| 20 | 21 | 22 |