MASON CITY — The world’s largest steam locomotive leaving Mason City this morning, on it’s way north toward Minnesota. The 1940s-era locomotive known as Big Boy Number 40-14 has been steaming its way from Omaha since the start of the week.Ed Dickens manages the Union Pacific’s steam program and says the big question everybody has asked for the last four decades is when the railroad company would restore a Big Boy locomotive. “For a long, long time, there was an idea that it just was impossible and so people have been told that it’s impossible because it’s too heavy, because it won’t do this, and you can’t do that, and all these different negative things about it, but the reality is that clearly it’s possible because you’re looking at it. What happens is when people hear these constant things about why it can’t be done, that just makes it more interesting when it’s finally done. I think that’s kind of what’s helped build the excitement around this locomotive because nobody ever thought they would ever see one run.”The Big Boy was parked overnight at the UP’s former crossing near 9th Northwest and North Jackson. Dickens says the crowds wanting to come see the locomotive have been tremendous, and commented about the number of people watching from the 12th Northwest overpass before Big Boy pulled out this morning. “The bridge is lined with people, and we see that everywhere, every town, every city. Every railroad crossing, no matter how isolated, has someone waiting there for this locomotive.”Dickens says Big Boy is completely different than the locomotives we see on the rails today. “It’s vastly different than the modern trains we run. It’s significantly larger than the other steam locomotive that we operate, the UP 844 and the locomotive that we used to run, the 3985. It’s just a very big, big powerful locomotive.’The big locomotive is one of only 25 that was manufactured and it was featured in Ogden, Utah, at a special event back in May to commemorate when the last spike was tapped in place at Promontory Point, creating America’s first transcontinental railroad. Big Boy was headed for stops in Albert Lea and Owatonna today.