Attendees take photographs and admire Union Pacific’s Big Boy No. 4014, the world’s largest operating steam engine locomotive, during a stop in Philadelphia on July 5, 2026. As part of the celebration for America’s 250th anniversary, the steam engine train is on tour for public display in multiple cities and states across the United States. Michelle Gustafson for NPR
Michelle Gustafson for NPR
Union Pacific Railroad’s Big Boy No. 4014– the world’s largest operating steam
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