A look at rare diesel locomotives still in regular service and the dwindling fleet of these unique and historic workhorses.

No. 4014 is the only one that is still in operation and is the world’s largest operating steam locomotive, Union Pacific said. ‘Big Boy,’ the 1.1 million pound train, passing through ...

Big Boy No. 4014 is the world’s largest operational steam locomotive and one of Union Pacific’s original engines. The locomotive rode the rails for 20 years from 1941 to 1961, clocking more ...

Union Pacific's Big Boy locomotive stops in Fort Worth 00:52. ... Colorado, Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma and Texas. The eight-week tour concludes later this month. ...