Railroads involved complex operations and employed extremely large amounts of capital and ran a more complicated business compared to anything previous. Consequently, they needed better ways to track costs. For example, to calculate rates they needed to know the cost of a ton-mile of freight. They also needed to keep track of cars, which could go missing for months at a time. This led to what was called "railroad accounting", which was later adopted by steel and other industries, and eventually became modern accounting.