In 1854, Philadelphia expanded its borders to include the surrounding suburbs, and after the Civil War its population swelled to several hundred thousand. By 1870 the Centennial Exposition was upcoming, and Philadelphia was rapidly changing.
Philadelphia's borders were extended in 1854 to include nearby suburbs, leading to a significant increase in its population to over several hundred thousand by the time of the Civil War. By 1870, preparations for the Centennial Exposition were underway, and Philadelphia was undergoing rapid changes.