Main Line (Long Island Rail Road)

The Main Line is a rail line owned and operated by the Long Island Rail Road in the U.S. state of New York. It begins as a two-track line at Long Island City station in Long Island City, Queens, and runs along the middle of Long Island about 95 miles (153 km) to Greenport station in Greenport, Suffolk County. At Harold Interlocking approximately one mile east of Long Island City, the tracks from the East River Tunnels and 63rd Street Tunnel into Manhattan intersect with the Main Line, which most trains use rather than using the Long Island City station.

Continuing east, five branches split from the Main Line. In order from west to east, they are:

• Port Washington Branch (at Harold Interlocking in Long Island City, Queens)
• Hempstead Branch (at Queens Interlocking along the Queens/Nassau County border)
• Oyster Bay Branch (at Nassau Interlocking, east of Mineola station)
• Port Jefferson Branch (at Divide Interlocking, east of Hicksville station)
• Central Branch (at Beth Interlocking, east of Bethpage station)—single non-electrified track with no stations, connecting the Main Line to the Montauk Branch

West of Ronkonkoma station, the Main Line is largely double tracked and electrified with 750V DC third rail, with trains governed by Automatic Block and Interlocking Signals and by Automatic Train Control. The line contains a third track between Divide and Queens Interlockings and a fourth track between Queens and Harold Interlockings. East of Ronkonkoma to Greenport, the line is not electrified and trains operate in non-signaled dark territory, with all train movements being governed by timetable and train order authority. Passenger service east of Hicksville station is covered by Ronkonkoma Branch timetables, as it is the final connecting point to other services.