Union Pacific Big Boy, the largest, most powerful steam locomotive in the world, tours the U.S.

As part of America's 250th birthday celebration, Union Pacific is sending Big Boy, the largest, heaviest and most powerful steam locomotive in the world, across the country. Ian Lee reports.

Source: [CBS News](https://www.cbsnews.com/video/union-pacific-big-boy-the-largest-most-powerful-steam-locomotive-in-the-world-tours-the-us/)