The following highways are numbered 181:

Canada

• Prince Edward Island Route 181

Chile

• Route 181-CH in Araucanía Region

India

• National Highway 181 (India)

Ireland

• R181 road (Ireland)

Japan

• Japan National Route 181

United Kingdom

• M181 motorway (East Butterwick-Scunthorpe)

United States

• Interstate 181 (former)
• U.S. Route 181
• Alabama State Route 181
• Arizona State Route 181
• Arkansas Highway 181
• California State Route 181
• Connecticut Route 181
• Florida State Road 181 (former)
• Georgia State Route 181 (former)
• Georgia State Route 181
• Illinois Route 181 (former)
• Iowa Highway 181 (former)
• K-181 (Kansas highway)
• Kentucky Route 181
• Louisiana Highway 181
• Maine State Route 181
• Maryland Route 181
• Massachusetts Route 181
• M-181 (Michigan highway) (former)
• Missouri Route 181
• New Jersey Route 181
• New Mexico State Road 181
• New York State Route 181 (former)
• North Carolina Highway 181
• Ohio State Route 181
• Pennsylvania Route 181
• South Carolina Highway 181
• Tennessee State Route 181
• Utah State Route 181 (former)
• Texas State Highway 181 (former)
  • Texas State Highway Loop 181
  • Farm to Market Road 181 (Texas)
• Virginia State Route 181
• Washington State Route 181
• Wisconsin Highway 181

Territories:

• Puerto Rico Highway 181