In 1794 Philadelphia was, with roughly 50,000 inhabitants, the country’s largest urban center. It was also the seat of the federal government and a haven for international refugees from all over the globe.

Taking into account the influx of refugees, along with the yellow fever epidemic of 1793 into account, provides an extreme example of how the city’s population could significantly fluctuate from year to year or even from month to month. In a very short time during the spring of 1793 well over 2,000 new émigrés arrived. The population swelled from the influx, but then quickly shrank to less than half as a result of the contagion.

Most likely, refugees fleeing the revolution in Haiti carried the disease with them. The blood-born pathogen was spread via mosquitoes and by the end of the summer nearly 5,000 Philadelphians had perished. More than 20,000 vacated their homes and did not return to the city until the following spring. It must have been a strange and difficult winter in Philadelphia that year.