Railways

• Main line (railway)
  Main line (railway)
  The Mainline or Main line of a railway is a track that is used for through trains or is the principal artery of the system from which branch lines, yards, sidings and spurs are connected....
  
  , the principal artery of a railway system
• Main Line of Public Works
  Main Line of Public Works
  The Main Line of Public Works was a railroad and canal system built by the Commonwealth of Pennsylvania in the 19th century. It ran from Philadelphia west through Harrisburg and across the state to Pittsburgh and connected with other divisions of the Pennsylvania Canal...
  
  , a railroad and canal system in Pennsylvania
  • Main Line (Pennsylvania Railroad)
    Main Line (Pennsylvania Railroad)
    The Main Line of the Pennsylvania Railroad was a rail line in the U.S. state of Pennsylvania, connecting Philadelphia with Pittsburgh via Harrisburg...
    
    , rail line from Philadelphia to Pittsburgh that evolved from the above
  • Philadelphia to Harrisburg Main Line
    Philadelphia to Harrisburg Main Line
    The Philadelphia to Harrisburg Main Line is an electrified rail line owned and operated by Amtrak in the U.S. state of Pennsylvania. The line runs from Zoo Interlocking in Philadelphia, where it meets the Northeast Corridor, west to Harrisburg , where electrification ends, along the former...
    
    , part of the Pennsylvania Railroad Main Line owned by Amtrak
• Main Line (Long Island Rail Road)
  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 in Long Island City and runs along the middle of Long Island about 95 miles to Greenport...
  
  , Long Island City to Greenport
• Main Line (NJ Transit)
  Main Line (NJ Transit)
  The Main Line is a rail line owned and operated by New Jersey Transit running from Suffern, New York to Hoboken, New Jersey. It runs daily commuter service and was once the north-south main line of the Erie Lackawanna Railroad...
  
  , formerly part of the Erie Railroad, Hoboken to Suffern
• SEPTA Main Line
  SEPTA Main Line
  The SEPTA Main Line is the section of the SEPTA Regional Rail system from the Zoo Interlocking in West Philadelphia to Lansdale Station in Lansdale, Pennsylvania...
  
  , shared segment to Glenside
• South Line, Tasmania
  South Line, Tasmania
  The South Line, also known as the Main Line and sometimes the North/South Line or the North–South Line, is a freight rail corridor connecting Hobart to the northern ports of Tasmania. The Railway Line was built by the Tasmanian Main Line Company...
  
  , Australia, also called the Main Line

Other transport

• Mainline (flight)
  Mainline (flight)
  A mainline flight is a flight operated by an airline's main operating unit, rather than by regional alliances, regional code-shares or regional subsidiaries...
  
  , an airline carrier's non-regional service
• A toll road
  Toll road
  A toll road is a privately or publicly built road for which a driver pays a toll for use. Structures for which tolls are charged include toll bridges and toll tunnels. Non-toll roads are financed using other sources of revenue, most typically fuel tax or general tax funds...
  
   system where all vehicles stop at various locations on the highway to pay a toll

Computing

• BitTorrent (software), nicknamed mainline by developers denoting its official origins

Music

• McKenna Mendelson Mainline
  McKenna Mendelson Mainline
  McKenna Mendelson Mainline is a seminal Canadian blues band, working the same English club circuit as the then up and coming bands Fleetwood Mac and Led Zeppelin...
  
  , a seminal Canadian blues band
• "Mainline", a song by KISS on their 1974 album Hotter Than Hell
  Hotter Than Hell
  Hotter Than Hell is the second studio album from hard rock band Kiss. It was released on October 22, 1974 and was certified Gold on June 23, 1977, having shipped 500,000 copies. The album was re-released in 1997 in a remastered version...
  
  

Defunct companies

• Midland Mainline
  Midland Mainline
  Midland Mainline was a British train operating company owned by the National Express Group and based in Derby. It was created after the privatisation of British Rail. Midland Mainline services operated from April 1996 to November 2007....
  
  , a defunct UK train operating company
• Mainline Freight
  Mainline Freight
  Mainline Freight was a trainload railfreight operator based in Islington, London England with operations extending to Yorkshire in the north and Somerset in the west...
  
  , a UK railfreight company
• First South Yorkshire
  First South Yorkshire
  First South Yorkshire is the largest bus operator in South Yorkshire, England. As a division of FirstGroup the company's legal name was, for a time, Mainline which operated it between 1993 and 1998, following the sale South Yorkshire Transport to its employees.-History:SYT was eventually sold to...
  
  , formerly "Mainline" (1993-1998), a large bus operator in South Yorkshire, England
• Mainline, a model railway models company now owned by Bachmann
  Bachmann Branchline
  Bachmann Branchline is a brand name of Bachmann Industries used for British outline 00 gauge model railways.Bachmann, a US company founded in 1835, was purchased by Kader Industries in 1987. Kader had previously produced models for Palitoy under the 'Mainline' brand...
  
  .