Frog war

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Sometimes the first railroad was built specifically to delay the completion of the second.

Division of costs

It is generally the case that the second railway to arrive has to bear the cost of the special trackwork needed to cross the first. This includes the cost of any interlocking tower or signal box. The latter is not necessarily to the disadvantage of the second railway, since it can signal its trains through the junction ahead of those belonging to the first railway.

Oil pipelines

In the early days oil mostly travelled by rail, but gradually oil companies built oil pipelines. Not wanting to lose business, railway companies often refused permission to oil companies for pipelines to cross their tracks.

Bridges and riverboats

Abraham Lincoln participated in a celebrated court case that decided that railroads had as much right to bridge rivers as the riverboat had the right to navigate those rivers. Nova Scotia's Shubenacadie Canal was rendered useless by a railway bridge built across it in 1858.

List of frog wars

United States

Note: The first railroad line built is the first one named.
* 1870s: Denver and Rio Grande Western Railroad vs. Atchison, Topeka and Santa Fe Railroad vs. Union Pacific Railroad in Colorado; three railroads vying for suitable mountain passes.
* December 2, 1870–January 9, 1871: The Erie Railroad vs. Morris and Essex Railroad's Boonton Branch (Delaware, Lackawanna and Western Railroad) at the west end of the Erie's Long Dock Tunnel in Jersey City, New Jersey.
* January 6 and January 7, 1876: The Mercer and Somerset Railway (Pennsylvania Railroad) vs. the Delaware and Bound Brook Railroad (Reading Railroad) in Hopewell, New Jersey.
* August 7–September 13, 1883: The Southern Pacific Railroad vs. the California Southern Railroad (a subsidiary of the Atchison, Topeka and Santa Fe Railway) at Colton, California (just outside of Los Angeles).
* March, 1886: The Erie Railroad vs. the New Jersey Junction Railroad (New York Central Railroad) at King's Bluff near Weehawken, New Jersey.
* September, 1891: The Central Railroad of New Jersey vs. the Jersey City, Newark and Western Railway (Lehigh Valley Railroad) in southern Jersey City, New Jersey.
* March, 1894: The Cape May and Millville Railroad (Pennsylvania Railroad) vs. the Tuckahoe and Cape May Railroad (Reading Railroad) at Woodbine Junction, New Jersey
* 1897: The Pennsylvania Railroad vs. the New Jersey Junction Connecting Railway (Lehigh Valley Railroad) in Jersey City, New Jersey.

United Kingdom

* Battle of Havant
* Nicky Line
* conflict of London and South Western Railway with the London, Brighton and South Coast Railway over the building of the Portsmouth branch.