Once they were a familiar sight: iron horses belching smoke and steam, chugging out of depots and racing across the countryside. Those spectacular steam locomotives are gone. But in this fascinating book, Karl Zimmermann, an authority on trains, takes young readers back to a colorful era of railroad history. He traces the development of the steam locomotive from early engines, such as the little Tom Thumb, to Big Boy, the largest locomotive ever built. He explains how steam locomotives work, how they are classified, why they were vanquished by the diesel; and why those magnificent machines still hold us spellbound. Chock-full of fascinating facts, and featuring stunning full-color and archival photographs, this book will fire the imagination of any young reader who ever dreamed of getting behind the throttle of a mighty steam locomotive.