Unidentified soldiers of Massachusetts Infantry Regiment in Union uniforms with swords on the platforms at Relay House train station on the Baltimore & Ohio Railroad in Halethorpe, Maryland. EHT Anthony. Library of Congress. https://lccn.loc.gov/2022631765

The Civil War arrived as big changes were afoot in American society. Cities were expanding in the more heavily populated areas like the northeast; demand for labor to run the new machinery of the Industrial Age meant that a large workforce lived within walking distance of the mills and factories. The majority of Americans still lived in rural areas, but the railroad made it easier for people to move around. When farming men, living a more isolated life on land, were suddenly put in close proximity in camps, they were at a disadvantage. Rural men were more likely to catch a contagious disease because they less exposure to illness and thus had no immunity. In addition to being exposed to more disease in general, urban workers were more likely than their rural counterpoints to have a smallpox vaccination at their places of work.