The following highways are numbered 3, H-3, PRI-3, AH3, E03 and R3. For roads numbered A3, see A3 roads. For roads numbered M3, see M3. For roads numbered N3, see N3. For roads numbered 3A, see 3A.

International

• AH3 Asian Highway 3
• E03 European route E03
• E003 European route E003
• Tripoli – Cape Town Highway

Albania

• A3 motorway (Albania)
• SH-3 Road in Albania from Kapshtice to Tirana.

Argentina

• National Route 3

Australia

New South Wales

• A3 (Sydney)

Northern Territory

• (Northern Territory)

Queensland

• M3/A3 (Brisbane)
• Burnett Highway (Queensland)
• State Route 3 (Queensland) – Isis Highway

South Australia

• Cross Road

Tasmania

• Tasman Highway

Victoria

• 
  • Eastern Freeway (Melbourne)
  • EastLink (Melbourne) (Toll)
  • Frankston Freeway
• 
  • Nepean Highway

Western Australia

• State Route 3 (Western Australia) – Reid Highway and Roe Highway

Austria

• Südost Autobahn

Belgium

• R3 (ring road)

Bulgaria

• Републикански път I-3
• Struma motorway (A3/E79)

Burma

• National Highway 3 (Burma)

Cambodia

• National Highway 3 (Cambodia)

Canada

• Alberta Highway 3 (Crowsnest Highway)
• British Columbia Highway 3 (Crowsnest Highway)
• Manitoba Highway 3
• New Brunswick Route 3
• Newfoundland and Labrador Route 3
• Nova Scotia Trunk 3
• Ontario Highway 3
• Prince Edward Island Route 3
• Quebec Route 3 (former)
• Saskatchewan Highway 3
• Yellowknife Highway (Northwest Territories Highway 3)
• Yukon Highway 3

China

• G3 Expressway

Costa Rica

• National Route 3

Czech Republic

• D3 motorway
• I/3 Highway (in Czech)

Djibouti

• RN-3 (Djibouti)

Dominican Republic

• DR-3

Eswatini

• MR3 road

Finland

• Vt 3 Finnish national road 3
• Åland Islands Highway 3

Germany

• A 3 Bundesautobahn 3
• B 3 Bundesstraße 3

Hong Kong

• Route 3 (Hong Kong)

Hungary

• M3 motorway (Hungary)
• Main road 3 (Hungary)

India

• National Highway 3 (India)
• National Highway 3 (India, old numbering)

Indonesia

• Indonesian National Route 3

Iran

• Freeway 3 (Iran)

Iraq

• Highway 3 (Iraq)

Ireland

• M3 motorway (Republic of Ireland)
• N3 road (Ireland)

Israel

• Highway 3 (Israel)

Italy

• Autostrada A3
• RA 3

Japan

• National Route 3
• Kyushu Expressway
  • Minamikyushu Expressway (branch of the Kyushu Expressway)
• Route 3 (Shuto Expressway) in the Shibuya area of Tokyo
• Route 3 (Nagoya Expressway)
• Kobe Route

Kazakhstan

• A3 highway (Kazakhstan)

Korea, South

• National Route 3

Laos

• R3A highway^[1]

Malaysia

• Second Link Expressway
• FT 3 Malaysia Federal Route 3

Mexico

• Mexican Federal Highway 3

Moldova

• Magistrala 3
• Road 3

New Zealand

• New Zealand State Highway 3
  • New Zealand State Highway 3A

Nigeria

• A3 highway (Nigeria)

Oman

• Route 3 (Oman)

Paraguay

• National Route 3

Philippines

• C-3 Circumferential Road 3
• R-3 Radial Road 3
• N3 highway (Philippines)
• E3 expressway (Philippines)

Poland

• A 3 Autostrada A3 (planned 1993-2001; unbuilt)
• S 3 Expressway S3
• DK 3 National road 3

Romania

• Drumul Naţional 3
• Autostrada A3

Russia

• M3 highway (Russia)

Sri Lanka

•  A3  Colombo-Puttalam Road
•  E03  Colombo–Katunayake Expressway

South Africa

• N3 (South Africa)
• M3 (Cape Town)
• M3 (Pretoria)

Taiwan (Republic of China)

• Freeway 3 (Taiwan)
• Provincial Highway 3 (Taiwan)

Thailand

• Thailand Route 3 (Sukhumvit Road)

Turkey

• O-3, a motorway in Turkey running from Edirne to Istanbul.

United Kingdom

• M3 motorway (Great Britain)
• A3 road (Great Britain)
• M3 motorway (Northern Ireland)
• A3 road (Northern Ireland)

United States

• Interstate 3 (proposed)
• Interstate A-3 (unsigned)
• Interstate H-3
• Interstate PR-3 (unsigned)
• U.S. Route 3
• New England Interstate Route 3 (former)
• Alabama State Route 3
• Alaska Route 3
• Arkansas Highway 3
• California State Route 3
• Colorado State Highway 3
• Connecticut Route 3
• Delaware Route 3
• Florida State Road 3
  • Florida State Road 3A (pre-1945) (former)
  • County Road 3 (Brevard County, Florida)
  • County Road 3 (Volusia County, Florida)
• Georgia State Route 3
  • Georgia State Route 3N (former)
  • Georgia State Route 3S (Thomaston) (former)
  • Georgia State Route 3W (Albany 1946–1957) (former)
  • Georgia State Route 3W (Albany 1960–1973) (former)
  • Georgia State Route 3W (Thomaston) (former)
  • Georgia State Route 3W (Atlanta–Marietta 1937–1946) (former)
  • Georgia State Route 3W (Atlanta–Marietta 1954–1955) (former)
  • Georgia State Route 3E (Thomaston) (former)
  • Georgia State Route 3E (Atlanta–Marietta) (former)
• Idaho State Highway 3
• Illinois Route 3
• Indiana State Road 3
• Iowa Highway 3
• K-3 (Kansas highway)
• Kentucky Route 3
• Louisiana Highway 3
  • Louisiana State Route 3 (former)
• Maine State Route 3
• Maryland Route 3
• Massachusetts Route 3
• M-3 (Michigan highway)
• Minnesota State Highway 3
  • County Road 3 (Anoka County, Minnesota)
  • County Road 3 (Chisago County, Minnesota)
  • County Road 3 (Goodhue County, Minnesota)
  • County Road 3 (Hennepin County, Minnesota)
  • County Road 3 (Ramsey County, Minnesota)
  • County Road 3 (St. Louis County, Minnesota)
• Mississippi Highway 3
• Missouri Route 3
  • Missouri Route 3 (1922) (former)
• Montana Highway 3
• Nebraska Highway 3 (former)
• Nevada State Route 3 (former)
• New Jersey Route 3
  • County Route 3 (Monmouth County, New Jersey)
    • County Route 3A (Monmouth County, New Jersey)
  • County Route 3 (Ocean County, New Jersey)
• New York State Route 3
  • New York State Route 3A (1930–1932) (former)
  • New York State Route 3A (1932–1935) (former)
  • New York State Route 3B (1930–1932) (former)
  • New York State Route 3B (1932–1935) (former)
  • New York State Route 3C (1930–1932) (former)
  • New York State Route 3C (1932–1935) (former)
  • New York State Route 3D (1931–1932) (former)
  • New York State Route 3D (1932–1935) (former)
  • New York State Route 3E (1930–1932) (former)
  • New York State Route 3E (1932–1935) (former)
  • New York State Route 3F (1931–1932) (former)
  • New York State Route 3F (1932–1935) (former)
  • New York State Route 3G (former)
  • County Route 3 (Allegany County, New York)
  • County Route 3 (Cattaraugus County, New York)
  • County Route 3 (Chemung County, New York)
  • County Route 3 (Dutchess County, New York)
  • County Route 3 (Genesee County, New York)
  • County Route 3 (Greene County, New York)
  • County Route 3 (Jefferson County, New York)
  • County Route 3 (Livingston County, New York)
  • County Route 3 (Montgomery County, New York)
  • County Route 3 (Niagara County, New York)
  • County Route 3 (Oneida County, New York)
  • County Route 3 (Ontario County, New York)
  • County Route 3 (Oswego County, New York)
  • County Route 3 (Otsego County, New York)
  • County Route 3 (Rensselaer County, New York)
  • County Route 3 (Schoharie County, New York)
  • County Route 3 (Schuyler County, New York)
  • County Route 3 (St. Lawrence County, New York)
  • County Route 3 (Steuben County, New York)
  • County Route 3 (Suffolk County, New York)
  • County Route 3 (Westchester County, New York)
• North Carolina Highway 3
• North Dakota Highway 3
• Ohio State Route 3
• Oklahoma State Highway 3
  • Oklahoma State Highway 3E
  • Oklahoma State Highway 3W
• Oregon Route 3
• Pennsylvania Route 3
• Rhode Island Route 3
• South Carolina Highway 3
• Tennessee State Route 3
• Texas State Highway 3
  • Texas State Highway Loop 3 (former)
  • Texas State Highway Spur 3
  • Texas Farm to Market Road 3
  • Texas Park Road 3
• Utah State Route 3 (former)
• Vermont Route 3
• Virginia State Route 3
• Washington State Route 3
  • Primary State Highway 3 (Washington) (former)
• West Virginia Route 3

Territories

• Guam Highway 3
• Interstate PR-3 (unsigned)
• Puerto Rico Highway 3
  • Puerto Rico Highway 3R

Uruguay

• Route 3 Gral. José Artigas

Zambia

• T3 road (Zambia)
• M3 road (Zambia)