In 1918, streetcars were the top urban transportation mode in the United States. And they were packed: Americans made about 140 trips per capita, about 15 billion trips total, that year.
Then came the Spanish flu. As influenza ripped through cities, crowded systems were forced to make health-centric changes, including requiring masks on passengers, limiting streetcar capacity, and staggering commute hours to keep riders distanced. Some vehicles were briefly decommissioned due to a shortage of operators. Still, the popularity of mass transit did not suffer dramatically in the succeeding years — at least not until the Great Depression put a quarter of the country out of work and, later, when the private automobile began to displace it.
