TAMA, IOWA - JUNE 01: People gather along the railroad tracks to watch as Union Pacific’s Big Boy No. 4014, the world’s largest operating steam locomotive, makes a stop in the city's downtown during its cross-country journey to celebrate America's 250th birthday on June 1, 2026 in Tama, Iowa. Between 1941 and 1944 Union Pacific commissioned 25 Big Boy locomotives, eight still remain, but the restored 4014 is the only one that is fully operational. (Photo by Scott Olson/Getty Images)