Big Boy No. 4014, World's Largest Steam Locomotive, Crosses US for 250th Birthday

The world's largest operating steam locomotive, Big Boy No. 4014, is traversing the United States in honor of America's 250th birthday. Weighing 1.2 million pounds and stretching 133 feet, the manually operated 1940s-era train has drawn crowds lining tracks from Pennsylvania to Colorado. After stops in Philadelphia for July 4 and 5, it continues through Ohio, Indiana, Illinois, Missouri, Kansas, and Colorado, returning to Wyoming by month's end. One of 25 Big Boys built by the American Locomotive Company between 1941 and 1944, it hauled supplies through the Wasatch Mountains. Only eight remain; No. 4014 is the sole operational one, restored by Union Pacific after being reacquired from RailGiants Train Museum in 2013. It retired from freight duty in December 1961 after over a million miles. The crew uses hand signals due to noise, and spectators can track its journey online.