The following highways are numbered 31:

International

• AH31 Asian Highway 31
• E31 European route E31

Australia

• Hume Highway
  • Hume Motorway
  • Hume Freeway
• – South Australia
  • Gorge Road
  • Little Para Road
  • South Para Road
  • Lyndoch Valley Road

Austria

• Burgenland Schnellstraße
• Ybbstal Straße

Burma

• National Highway 31 (Burma)

Canada

• Alberta Highway 31
• British Columbia Highway 31
• Manitoba Highway 31
• Ontario Highway 31 (former, now Ottawa Road 31)
• Quebec Autoroute 31
• Saskatchewan Highway 31

Czech Republic

• part of I/31 Highway; Czech: Silnice I/31

France

• A31 autoroute

Germany

• Bundesautobahn 31
• Bundesstraße 31

Iceland

• Route 31 (Iceland)

India

• NH 31

Iran

• Road 31

Ireland

• N31 road (Ireland)

Israel

• Highway 31 (Israel)

Italy

• Autostrada A31 (Italy)

Japan

• Japan National Route 31
• Hiroshima-Kure Road

Korea, South

• National Route 31

Netherlands

• A31 motorway (Netherlands)

New Zealand

• New Zealand State Highway 31

South Africa

• M31 road (Johannesburg)

Sri Lanka

•  A31  A31 highway (Sri Lanka)

Thailand

• Thailand Route 31 (Vibhavadi Rangsit Road)

Turkey

• O-31, a motorway in Turkey running from İzmir to Aydın.

United Kingdom

• British A31 (Bere Regis-Guilford)
• A31 road (Isle of Man)

United States

• Interstate 31 (former)
• U.S. Route 31
  • U.S. Route 31W
  • U.S. Route 31E
• Arkansas Highway 31
• California State Route 31
  • County Route J31 (California)
  • County Route S31 (California)
• Connecticut Route 31
• Florida State Road 31
• Georgia State Route 31
• Hawaii Route 31
• Idaho State Highway 31
• Illinois Route 31
• Iowa Highway 31
• K-31 (Kansas highway)
• Louisiana Highway 31
• Maryland Route 31
• Massachusetts Route 31
• M-31 (Michigan highway) (former)
• Minnesota State Highway 31
  • County Road 31 (Anoka County, Minnesota)
  • County Road 31 (Dakota County, Minnesota)
  • County Road 31 (Hennepin County, Minnesota)
  • County Road 31 (Ramsey County, Minnesota)
• Missouri Route 31
• Nebraska Highway 31
• Nevada State Route 31 (former)
• New Hampshire Route 31
• New Jersey Route 31
  • County Route 31 (Bergen County, New Jersey)
    • County Route S31 (Bergen County, New Jersey)
  • County Route 31 (Monmouth County, New Jersey)
  • County Route 31 (Ocean County, New Jersey)
• New Mexico State Road 31
• New York State Route 31
  • New York State Route 31F
  • County Route 31 (Dutchess County, New York)
  • County Route 31 (Franklin County, New York)
  • County Route 31 (Greene County, New York)
  • County Route 31 (Livingston County, New York)
  • County Route 31 (Montgomery County, New York)
  • County Route 31 (Niagara County, New York)
  • County Route 31 (Orleans County, New York)
  • County Route 31 (Otsego County, New York)
  • County Route 31 (Suffolk County, New York)
  • County Route 31 (Ulster County, New York)
  • County Route 31 (Wyoming County, New York)
• North Carolina Highway 31 (former)
• North Dakota Highway 31
• Ohio State Route 31
• Oklahoma State Highway 31
• Oregon Route 31
• Pennsylvania Route 31
• South Carolina Highway 31
• Tennessee State Route 31
• Texas State Highway 31
  • Texas State Highway Spur 31
  • Farm to Market Road 31
  • Texas Park Road 31
• Utah State Route 31
• Vermont Route 31
• Virginia State Route 31
  • Virginia State Route 31 (1923-1933) (former)
• Washington State Route 31
• West Virginia Route 31
• Wisconsin Highway 31
• Wyoming Highway 31

Territories

• Puerto Rico Highway 31