At the height of the early twentieth century, a single word could bring a train, a hotel, a ship, or an entire neighborhood to a sudden halt: smallpox.
Before modern eradication, smallpox was one of the most feared diseases in the world. It spread easily, left survivors scarred, and killed with a brutality that made public health officials act fast.
When a suspected case appeared in a public place, there was rarely time for debate. Authorities moved in, sealed off the area, and made sure everyone who may have been exposed was accounted for.

That is what happened in Philadelphia in December 1913, when the Pittsburg Express arrived with a terrifying discovery onboard. One of the passengers was found to have smallpox, and attention quickly turned to the men who had shared the smoking car with him. Thirty-nine of them were vaccinated before they were allowed to leave the train.
Here is the 1913 report of a quarantined train, a smoking car full of exposed passengers, and the swift vaccination of 39 men before anyone was allowed to go home.
Quarantine Train to Vaccinate 39

PHILADELPHIA, Pennsylvania. — Following the discovery by the health authorities that a man who had been a passenger on the Pittsburg Express arriving her early today had smallpox, 39 men who been in the smoking car were vaccinated before they were allowed to leave.
The train was quarantined until the doctor finished.
Women passengers who were not permitted to join their husbands became hysterical.
Source: Bismarck Daily Tribune. Bismarck, N.D. December 17, 1913.

