The following highways are numbered 203:

• Manitoba Provincial Road 203
• Newfoundland and Labrador Route 203
• Nova Scotia Route 203
• Prince Edward Island Route 203
• Quebec Route 203

• Route 203-CH in Los Ríos Region

• China National Highway 203

• National Route 203

• National Highway 203 (India)

• Japan National Route 203

• Belgium B203

• Thailand Route 203

• A203 road
• B203 road

• Alabama State Route 203
• California State Route 203
• Connecticut Route 203
• Georgia State Route 203
• Illinois Route 203
• Indiana State Road 203
• Iowa Highway 203 (former)
• K-203 (Kansas highway)
• Kentucky Route 203
• Maine State Route 203 (former)
• Massachusetts Route 203
• M-203 (Michigan highway)
• Montana Secondary Highway 203
• New Mexico State Road 203
• New York State Route 203
• Ohio State Route 203
• Oregon Route 203
• Pennsylvania Route 203 (former)
• South Carolina Highway 203
• South Dakota Highway 203
• Tennessee State Route 203
• Texas State Highway 203
  • Texas State Highway Spur 203
• Utah State Route 203
• Virginia State Route 203
• Washington State Route 203

Territories

• Puerto Rico Highway 203