"Steam days" refer to a period in history when steam-powered locomotives were the primary mode of transportation for trains. This era began in the early 19th century and continued until the mid-20th century, when diesel and electric engines became more common. Steam engines used coal or wood to heat water in a boiler, creating steam that powered the train's movement. During steam days, railroads played a crucial role in the industrial revolution, facilitating the transport of goods and people across long distances. Famous steam locomotives, such as the Flying Scotsman and Mallard, became iconic symbols of this time, showcasing the engineering marvels of their day.