A Line or A-line may refer to:
Transport United States A (Los Angeles Railway), a former streetcar service in California A (New York City Subway service), a rapid transit line A Line (Los Angeles Metro), a light rail line in Los Angeles County, California A Line (RTD), a commuter rail line in Colorado A Line (Valley Metro), a light rail line in Arizona Metro A Line (Minnesota), a bus rapid transit line in Minneapolis-Saint Paul, Minnesota RapidRide A Line, a bus route in King County, Washington Atlantic Coast Line Railroad, a former railroad in the southern US Main Line (Atlantic Coast Line Railroad)
Other countries A-Line (Hamilton), a planned rapid transit line in Hamilton, Ontario, Canada Line A (Buenos Aires Underground), in Argentina RER A, a commuter rail line in Paris, France
Other uses A-line (clothing), a style of skirt or dress Arterial line, a thin catheter inserted into an artery A-line, a finding in medical ultrasound of the lung A-line bob, one of several bob cut types
See also A–A line Aline (disambiguation) Line A (disambiguation) Line (disambiguation)