Fort Jefferson occupies about ten acres, roughly the same size as a major league baseball stadium. Inside the brick walls of the fort, the grassy central area, known as the Parade ground, is about the same size as a baseball stadium’s playing field.
Living quarters for soldiers and officers, gunpowder magazines, carpenter shop, bakery, chapel, theater, kitchens, storehouses, and other buildings required to maintain the fort were located around the periphery of the Parade ground. The remaining central grassy area was used for drills, inspections, a small garden, and sports, including baseball, which was exploding in popularity as America’s national pastime. Most of the structures are gone now, victims of the tropical climate, hurricanes, and fires.
Fort Jefferson was essentially a very small and densely populated city. Almost 2,000 people lived there during the Civil War years just before Dr. Mudd arrived. The peak military population was 1,729, but there were also many civilians, a fluctuating number of military and civilian prisoners, and a few slaves, living there. They were all engaged in the construction and maintenance of the fort. Occupations included machinists, carpenters, plasterers, bakers, butchers, painters, blacksmiths, masons, and general laborers. There were also lighthouse keepers and their families, cooks, a civilian doctor and his family. A number of officers brought their families, including children, and a limited number of enlisted personnel brought wives who served as laundresses (typically four per company). The 22 slaves working at Fort Jefferson in 1863 were freed shortly after Lincoln’s Emancipation Proclamation.
With the war over, the population of Fort Jefferson began to decline and had dropped to 1,013 by the time Dr. Mudd arrived in July 1865. Of these, 486 were soldiers or civilians and 527 were prisoners. When Dr. Mudd was released in March 1869, the population had dropped to 282, of whom only 35 were prisoners.