The development of the steam locomotive arguably reached its zenith on the railroads of North America. On those lines massive articulated machines worked hard for their living, mostly hauling incredibly long (by UK standards) freight trains on which the economy of the United States of America relied.

Unsurprisingly, in view of the enormity of these machines, few have the resources to restore the survivors and even fewer can afford to run them. Notable amongst those who can and do is the famous Union Pacific Railroad, which still even has its very last-built steam locomotive alive today and on its roster.

That locomotive is Northern type 4-8-4 no.844 - known as The Living Legend - and it is featured in this programme, working across the old West together with its stablemate UP 3985 - the Challenger. Other UP engines - and those of other railroads - are to be seen working on railroads across the continent including Consolidations, Mikados and classic American types. American narrow-gauge locomotives are also massive - easily bigger than most European machines - and examples of these can be seen in Colorado and New Mexico working on lines that climb the Rockie Mountains. Sit back and watch these locos exude power!