The first transcontinental railroad in the USA was completed in 1869. In the following years, until the turn of the twentieth century, many more railroads were built by different companies. Passenger trains declined from the 1950s and today there is only a minimal long-distance passenger service operated by Amtrak, leaving the railroads to concentrate on moving freight. From the 1970s until the 1990s many railroads merged to give the two main railroads...