They waited more than two hours — kicking rocks, whittling, talking about trains or pressing hand-held scanners to their ears — until, at last, it happened.

“Whistle!” Lawrence resident Richie Kennedy shouted at precisely 1:10 p.m. Wednesday. “Heard the whistle!”

6News video; 61-year-old steam engine rolls through Lawrence

Kennedy aimed his camera at the stretch of train tracks near the Lawrence Visitor Center and shouted “Incoming!”

Around the curve roared a million-pound piece of America’s history: the Union Pacific “Challenger,” the world’s largest operating steam locomotive.

Within seconds, it was gone.

The 1943 locomotive, used by the railroad these days for public relations purposes, passed through Lawrence en route to Houston, where it will be displayed during the Feb. 1 Super Bowl XXXVIII festivities.

Wilford Aday, Lawrence, a retired Santa Fe railroad conductor of 44 years, gives a thumbs-up to the steam locomotive Challenger as she blows her whistle by the Union Pacific Depot and heads east toward Kansas City. The Challenger, the world's largest operating steam locomotive, passed through Lawrence on Wednesday for a nine-state, 3,500-mile tour to Houston, where it will be on public display during Super Bowl XXXVIII activities.

Since before 11 a.m., Kennedy and about a dozen other train enthusiasts had been standing near the tracks waiting to catch a glimpse. Both Kennedy and Bob Harpool of Excelsior Springs, Mo., used scanners with antennae the size of fencing foils to monitor the train’s eastward progress.

Kennedy, 24, caught wind of the engine’s visit at an online train fan club.

Harpool, who works in accounting, said he considered the steam engine to be a romantic subject because of its historical significance.

“That’s what built our country,” he said. “It’s almost like it’s alive — It’s going, ‘Chuff! Chuff!'”

Retired Santa Fe railroad conductor Wilford Aday, 66, Lawrence, whittled a stick as he waited. He saw the locomotive a few years ago, the most recent time it passed through Lawrence.

“I just kind of like to see it thunder by and see the power,” he said.

After the train passed going about 40 mph, Harpool assessed whether it had been worth the wait.

“Maybe. It’s dubious,” he said. “Well, that was something.”

David Balmilero, 6, Lawrence, plugs up his ears as a train blows its horn and passes the Lawrence Visitor Center. Balmilero was with his mother, Marie Balmilero, Lawrence, and friends Wednesday as they waited for the steam locomotive Challenger to pass. Balmilero and his friends enjoyed the loud diesel trains but had to leave for school before the Challenger ran through Lawrence behind schedule.

6News video; 61-year-old steam engine rolls through Lawrence Union Pacific Challengers history