In the 1860s, a number of railroad developments came into being. In 1869, four years after the Civil War ended, the Union Pacific railroad line was connected to the Central Pacific line and the world's longest railroad—1,776 miles of steel track—was completed. The transcontinental railroad line, which was subsidized by government funds from the 1862 Pacific Railroad Act, had taken years to finish. The project involved an extensive amount of tearing down forests, tunneling through earth, and constructing bridges to complete, but once it was done, it changed the face of transportation.

Eight years later, in 1877 when Twain wrote "The Invalid's Story," railroads in the United States were in their Golden Age and trains were the dominant mode of transportation for both people and goods. Originally, this included only nonperishable items. In the early 1870s, however, Gustavus Franklin Swift, founder of the meat-packing firm, Swift...