Giant 'Big Boy' train helps celebrate America's 250th birthday

Under deep blue skies, Union Pacific’s Big Boy, the world’s largest operating steam locomotive, heads east near Cheyenne, Wyoming, as it begins a two-month trip to the East Coast for national 250th celebrations.

Union Pacific’s Big Boy, the world’s largest operating steam locomotive, pulls out of the Cheyenne rail yard as it begins a two-month trip to the East Coast for national 250th celebrations.

Union Pacific’s Big Boy, the world’s largest operating steam locomotive, pulls out of the Cheyenne rail yard as it begins a two-month trip to the East Coast for national 250th celebrations.

Ed Dickens, a locomotive engineer and senior manager of steam operations for Union Pacific, leans out the window of the Big Boy locomotive is it leaves Cheyenne, Wyoming, to begin a two-month trip to the East Coast for national 250th celebrations.

A railfan captures the Union Pacific Big Boy train as it begins its journey from Cheyenne, Wyoming, to the east coast for 250th anniversary celebrations.

Union Pacific’s Big Boy, the world’s largest operating steam locomotive, heads east near Cheyenne, Wyoming, as it begins a two-month trip to the East Coast for national 250th celebrations.

A railfan captures the Union Pacific Big Boy train as it begins its journey from Cheyenne, Wyoming, to the east coast for 250th anniversary celebrations.

An American flag decorates the side of a water tender serving the Union Pacific Big Boy locomotive, which is the world’s largest operating steam locomotive.

A worker passes by the Union Pacific Big Boy locomotive, the world’s largest operating steam locomotive, at the Union Pacific steam shop in Cheyenne, Wyoming.

A worker looks out upon the Union Pacific Big Boy locomotive, the world’s largest operating steam locomotive, at the Union Pacific steam shop in Cheyenne, Wyoming.

An American flag flies over the Union Pacific Big Boy locomotive, the world’s largest operating steam locomotive, at the Union Pacific steam shop in Cheyenne, Wyoming.

A worker prepares the Union Pacific Big Boy locomotive, the world’s largest operating steam locomotive, at the Union Pacific steam shop in Cheyenne, Wyoming.

A worker passes by the Union Pacific Big Boy locomotive, the world’s largest operating steam locomotive, at the Union Pacific steam shop in Cheyenne, Wyoming.

A safety tagout system hangs from the cab of the Union Pacific Big Boy locomotive, the world’s largest operating steam locomotive, at the Union Pacific steam shop in Cheyenne, Wyoming. The tags help keep track of workers in and around the locomotive, providing a manual safety check.

Union Pacific’s Ed Dickens, the senior manager of steam operations, explains how the Big Boy locomotive, the world’s largest operating steam locomotive, burns fuel oil to make steam, which then powers pistons to turn the drive wheels, at the UP steam shop in Cheyenne, Wyoming.

Union Pacific workers alongside the Big Boy locomotive, the world’s largest operating steam locomotive, as seen at the UP steam shops in Cheyenne, Wyoming.

Union Pacific workers alongside the Big Boy locomotive, the world’s largest operating steam locomotive, as seen at the UP steam shops in Cheyenne, Wyoming.

A new decoration on the front of the Union Pacific Big Boy locomotive heralds the 250th anniversary of the United States. Big Boy, the world’s largest operating steam locomotive, is touring the country to mark the railroad’s contributions to national success.

A Union Pacific worker is dwarfed by the Big Boy locomotive, the world’s largest operating steam locomotive, at the UP steam shops in Cheyenne, Wyoming.

A sticker at the Union Pacific steam shops in Cheyenne, Wyoming.

The American flag flies about the Union Pacific railroad flag at the UP steam shop in Cheyenne, Wyoming.