The last of the world’s largest steam engines will come through eastern Oklahoma Saturday.

Union Pacific took delivery on Engine 4014 in December of 1941. It's the last of what they called "Big Boys," and it's back on the rails and coming to Oklahoma as part of a cross country tour.

On Friday afternoon, a crowd of thousands waited in Russellville, Arkansas, to see the 600-ton steam engine pull in. It's the largest one ever built for Union Pacific, the last one running.

"That's a massive train," said Reicker Mills of Russellville. "It's massive."

At every stop, fans take countless photos, and everyone wants to shake the hand of Engineer Ed Dickens.

 "Running a steam locomotive in modern times isn't easy," Dickens said. "It involves a lot of money, a lot of fuel, a lot of grease and a lot of patience."

Union Pacific restored 4014 to celebrate the 150th anniversary of the transcontinental railroad. At every stop, rail workers stand by those 6-foot tall wheels to grease it up - to go again. Hardly anyone can remember seeing anything close to it.

"Not this big," said Don Hall of Perryville, Arkansas. "I rode one like it, but that was in first grade."

Engine 4014 was in use for 19 years, then it sat in a California museum for 50 years until Union Pacific restored it. This tour puts history right back on the rails.

The Union Pacific Big Boy will head through Oklahoma with brief stops in Sallisaw, Gore, Fort Gibson, Wagoner, Claremore, and Nowata - then on to Coffeyville.

Hear from Engineer Ed Dickens: