The following highways are numbered 320:

Canada

• Newfoundland and Labrador Route 320
• Nova Scotia Route 320
• Saskatchewan Highway 320

China

• China National Highway 320

Costa Rica

• National Route 320

India

• National Highway 320 (India)

Japan

• Japan National Route 320

United States

• U.S. Route 320 (former)
• Arkansas Highway 320
• Connecticut Route 320
• Florida State Road 320
  • County Road 320 (Florida)
• Georgia State Route 320
• Hawaii Route 320
• Kentucky Route 320
• Louisiana Highway 320
• Maryland Route 320
• Montana Secondary Highway 320
• Nevada State Route 320
• New Mexico State Road 320
• New York State Route 320
• Ohio State Route 320
• Pennsylvania Route 320
• Puerto Rico Highway 320
• Tennessee State Route 320
• Texas:
  • Texas State Highway 320
  • Texas State Highway Loop 320 (former)
  • Farm to Market Road 320
• Utah State Route 320
• Virginia State Route 320
• Wyoming Highway 320