A branch line is a secondary railway line which branches off a more important through route, usually a main line. A very short branch line may be called a spur line. David Blyth Hanna, the first president of the Canadian National Railway, said that although most branch lines cannot pay for themselves, they are essential to make main lines pay.
Many British branch lines were closed as a result of the "Beeching Axe" in the 1960s, although some have been re-opened as heritage railways.
The smallest branch line that is still in operation in the UK is the Stourbridge Town Branch Line from Stourbridge Junction going to Stourbridge Town. Operating on a single track, the journey is 0.8 miles (1.3 kilometres) long and the train takes around two and a half minutes to complete its journey.
Examples of spur lines in Singapore include: Changi Extension Line.
Examples of spur lines in Hong Kong include: Lok Ma Chau Spur Line, South Tseung Kwan O Spur Line, Racecourse Spur Line.
In North America, little-used branch lines are often sold by large railroads to become new common carrier short-line railroads of their own. Throughout the United States and Canada, branch lines link smaller towns too distant from the main line to be served efficiently, or to serve a certain industrial site such as a power station either because of a location away from the main line or to reduce congestion. They were typically built to lower standards, utilizing lighter rail and shallow roadbeds when compared to main lines. In the United States, abandonment of unproductive branch lines was a byproduct of deregulation of the rail industry through the Staggers Act.