Transportation
- B (New York City Subway service), a subway route in New York
- B-Line (Vancouver), a bus rapid transit system in Vancouver
- B-Line (Norfolk Southern), a freight rail line in Virginia
- Green Line "B" Branch, a light rail line in Boston
- Line B (Buenos Aires Metro), a subway route in Buenos Aires
- Line B (Prague Metro), a subway route in Prague
- Mexico City Metro Line B, a rapid transit line in Mexico City
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