Mainline, Main line, or Main Line may refer to:
The main line, or mainline in American English, 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. It generally refers to a route between towns, as opposed to a route providing suburban or metro services. For capacity reasons, main lines in many countries have at least a double track and often contain multiple parallel tracks. Main line tracks are typically operated at higher speeds than branch lines and are generally built and maintained to a higher standard than yards and branch lines. Main lines may also be operated under shared access by a number of railway companies, with sidings and branches operated by private companies or single railway companies.
Railway points (UK) or switches (US) are usually set in the direction of the main line by default. Failure to do so has been a factor in several fatal railway accidents, for example the Buttevant Rail Disaster in Ireland, and the Graniteville train disaster in the US.
The Main line (from the German Mainlinie, or line on the Main River) refers to the historical and political boundary between North and South Germany. The line delimitates the spheres of influence of Austria and Prussia within the German Confederation during the 19th century. The seat of the German Confederation, Frankfurt am Main, sat upon this line.
Eventually the Main line became the southern boundary of the North German Confederation. As such, the Main line did not follow the Main river exactly; rather, the line went east to west: first, along the northern border of the Kingdom of Bavaria; then, along the river Main to Mainz; and finally, along the Western border of the Grand Duchy of Hesse and the Bavarian Palatinate towards the French border. The line split Hesse at Frankfurt am Main; however, the entirety of Frankfurt am Main belonged to the North German Confederation. Today, Main line is viewed as the boundary between North and South Germany. Both regions have distinct linguistic and cultural differences.
The Ōu Main Line (奥羽本線, Ōu-honsen) is a railway line in Japan, operated by the East Japan Railway Company (JR East). It connects Fukushima Station through Akita Station to Aomori Station. Since the opening of the Yamagata Shinkansen on July 1, 1992, the Fukushima–Yamagata section (as well as the Yamagata–Shinjō section since 1999) is sometimes referred to as the Yamagata Line. The name of the line as a whole refers to the ancient provinces of Mutsu (陸奥) and Dewa (出羽), as it connects both ends of Mutsu by passing north-south through Dewa.