List of highways numbered 400

The following highways are numbered 400:

Canada

• Ontario Highway 400

Japan

• Japan National Route 400

Korea, South

• Capital Region Second Ring Expressway

Turkey

• , a west-east state road in Turkey running from Datça, Muğla Province to Esendere at the Iranian border.

United States

• U.S. Route 400
• Arkansas Highway 400
• Florida State Road 400
• Georgia State Route 400
• Louisiana Highway 400
• Nevada State Route 400
• New York:
  • New York State Route 400
  • County Route 400 (Erie County, New York)
• North Carolina Highway 400
• Pennsylvania Route 400 (official designation for Pennsylvania Route 380)
• Tennessee State Route 400
• Texas:
  • Texas State Highway Spur 400
  • Farm to Market Road 400
• Virginia State Route 400
  • Virginia State Route 400 (former)