Blue Line
- A (New York City Subway service)
- A Line (Los Angeles Metro)
- Abuja Light Rail
- Atlantic City Line
- Bannan line
- Barcelona Metro line 5
- Barcelona Metro line 6
- Blue Line (BART)
- Blue Line (Bangkok)
- Blue Line (CTA)
- Blue Line (Calgary)
- Blue Line (CapMetro)
- Blue Line (Chennai Metro)
- Blue Line (DART)
- Blue Line (Delhi Metro)
- Blue Line (Dubai Metro)
- Blue Line (Hyderabad Metro)
- Blue Line (Kolkata Metro)
- Blue Line (Lagos Transit)
- Blue Line (Lisbon Metro)
- Blue Line (Lucknow Metro)
- Blue Line (MARTA)
- Blue Line (MBTA)
- Blue Line (Mexico City Metro)
- Blue Line (Mexico City Metrobús)
- Blue Line (Montreal Metro)
- Blue Line (Mumbai Metro)
- Blue Line (Namma Metro)
- Blue Line (New York State)
- Blue Line (Pittsburgh)
- Blue Line (RTA Rapid Transit)
- Blue Line (SacRT)
- Blue Line (San Diego Trolley)
- Blue Line (Sound Transit)
- Blue Line (St. Louis MetroLink)
- Blue Line (Stockholm Metro)
- Blue Line (TRAX)
- Blue Line (Washington Metro)
- Blue Line (airline)
- Blue Line (album)
- Blue Line (withdrawal line)
- Blue Line International
- Blue line (Taichung MRT)
- Blue line (ice hockey)
- BlueLine Grid
- Busan Metro Line 4
- C (New York City Subway service)
- Downtown Line
- E (New York City Subway service)
- Full Negative (or) Breaks
- H Line (RTD)
- Harlem Line
- Hoboken–33rd Street
- Hy Buller
- IND Eighth Avenue Line
- Island line (MTR)
- JFK Express
- K Eighth Avenue Local
- KA Commuter line Jakarta Kota–Cikarang
- Line 1 (Riyadh Metro)
- Line 1 (São Paulo Metro)
- Line 2 (Beijing Subway)
- Line 3 Scarborough
- Line 4 (O-Train)
- Lynx Blue Line
- MAX Blue Line
- Manila Light Rail Transit System Line 2
- Market–Frankford Line
- Metro Blue Line (Minnesota)
- N Judah
- Newark Light Rail
- North Jersey Coast Line
- Paris Métro Line 2
- Piccadilly line
- Port Jefferson Branch
- Rapid Ride
- Rockaway Park Shuttle
- Seoul Subway Line 1
- Seoul Subway Line 4
- Sheffield Supertram
- Staten Island Railway
- Swift Blue Line
- T (New York City Subway service)
- Tomorrowland Transit Authority PeopleMover
- Trinity Railway Express
- Tyne and Wear Metro
- Victoria line
- Viva Blue
- West Hempstead Branch
- Yokohama Municipal Subway Blue Line