Your Ancestors Knew Death in Ways You Never Will

Other than cholera and typhus, most of those were childhood diseases that adults were immune to because they had survived them, so the chart is a parabola of parental grief, each spike another nail in a hundred small coffins.

The death rate began dropping after the 1860s. New Yorkers — both citizens and doctors — had finally stopped arguing and reached consensus on some basic issues.

First of all, most finally accepted the “germ theory” of disease, acknowledging that it was caused by invisible enemies, not by swamps, trash, manure or the other nuisances that underlay the “miasma theory,” which held that bad smells caused disease. (Only a century earlier, Americans had given up on the “humors theory,” which posited that disease was caused by imbalances among blood, urine, sweat and bile that had to be rebalanced by bleeding, sweating or purging.)

They also agreed that whether immigrants had brought some diseases or simply suffered from them, no one was safe until everyone was safe, so they made public health universal.

As a result, New Yorkers took certain steps — sometimes very expensive and contentious, but all based on science: They dug sewers to pipe filth into the Hudson and East Rivers instead of letting it pool in the streets. In 1842, they built the Croton Aqueduct to carry fresh water to Manhattan. In 1910, they chlorinated its water to kill more germs. In 1912, they began requiring dairies to heat their milk because a Frenchman named Louis Pasteur had shown that doing so spared children from tuberculosis. Over time, they made smallpox vaccination mandatory.

Libertarians battled almost every step. Some fought sewers and water mains being dug through their properties, arguing that they owned perfectly good wells and cesspools. Some refused smallpox vaccines until the Supreme Court put an end to that in 1905, in Jacobson v. Massachusetts.

In the Spanish flu epidemic of 1918, many New Yorkers donned masks but 4,000 San Franciscans formed an Anti-Mask League. (The city’s mayor, James Rolph, was fined $50 for flouting his own health department’s mask order.) Slowly, science prevailed, and death rates went down.