How density, poverty, and infrastructure turned American cities into biological experiments—and how disease forced the modern state into existence
According to a British Medical Journal poll, sanitation reform was the greatest medical advance of the last 150 years.
Clean water and proper sewage disposal has saved more lives than any other single intervention.
2.6 billion people (40% of Earth's population) lack access to a toilet.
Result: 1.5 million children die yearly from diarrheal diseases caused by contaminated water.
In urban slums without sewage systems, residents defecate in plastic bags and then throw them—hence "flying toilets" or "helicopter toilets."
Why this happens: No access to toilets, no municipal sewage infrastructure, overcrowding makes outdoor defecation impossible.
Health consequences: Waste ends up in streets, drainage ditches, and water sources—spreading disease throughout dense neighborhoods.
The absence of sanitation infrastructure creates conditions identical to 19th-century American cities.
Density Without Infrastructure
America's largest cities experienced unprecedented population explosions between 1880 and 1920.
+366%
1880–1920
1880: 1.2 million
1920: 5.6 million
Added 4.4 million people in 40 years
+437%
1880–1920
1880: 503,000
1920: 2.7 million
Fastest-growing major city
+115%
1880–1920
1880: 847,000
1920: 1.8 million
Doubled in 40 years
Chicago's 1880–1890 growth: +118.6% in a single decade. The city more than doubled in just 10 years.
500,000+ people
living in
15,000 tenements
Average: 33 people per building
Tenements weren't temporary solutions—they became permanent features of urban life.
Two-story building housing 102 people
Sharing one privy
The poorest families—recent immigrants, Black families—lived here. Your economic position literally determined whether you lived or died.
Basement apartments were literally below ground level—which meant they were below the level of the street's drainage and sewage.
The "slime": A combination of moisture seeping through walls, mold, sewage backup, and accumulated filth that created a perpetually damp, toxic coating on walls and floors.
Health impact: Tuberculosis thrives in damp, dark, poorly ventilated spaces. Basement dwellers had the highest TB death rates in the city. Infant mortality in basements was catastrophic—in some buildings, 1 in 4 children died before age 5.
A privy vault was an outdoor toilet—essentially a pit in the ground, often just a wooden box over a hole, where human waste accumulated until someone paid to have it removed.
Why they failed: In densely packed tenement districts, privies were shared by dozens or even hundreds of people. They filled quickly, overflowed regularly, and were located too close to buildings and water sources. Cities had few regulations about placement or maintenance.
The contamination cycle: Waste seeped from privies through soil into groundwater. Wells drew from that same groundwater. Families drank contaminated water. Cholera, typhoid, and dysentery spread rapidly because people were literally drinking water contaminated with human feces.
This wasn't understood until the 1880s–1890s when germ theory gradually replaced miasma theory. Until then, people knew privies were disgusting, but didn't understand the direct connection to waterborne disease.
The deadly connection between privies and wells
Waste from privies seeped through soil into groundwater, contaminating the wells families drew drinking water from.
Cholera, typhoid, and dysentery spreading through entire neighborhoods.
A privy vault was an outdoor toilet—essentially a pit in the ground, often just a wooden box over a hole, where human waste accumulated until someone paid to have it removed.
Why they failed: In densely packed tenement districts, privies were shared by dozens or even hundreds of people. They filled quickly, overflowed regularly, and were located too close to buildings and water sources. Cities had few regulations about placement or maintenance.
The contamination cycle: Waste seeped from privies through soil into groundwater. Wells drew from that same groundwater. Families drank contaminated water. Cholera, typhoid, and dysentery spread rapidly because people were literally drinking water contaminated with human feces.
This mechanism wasn't understood until the 1880s–1890s when germ theory gradually replaced miasma theory. Until then, people knew privies were disgusting, but didn't understand the direct connection to waterborne disease.
By 1865, New York faced a housing crisis:
First law to attempt to regulate housing in America
Required:
James Ware's dumbbell design became the standard solution
The 1879 Tenement House Act required apartments to have windows for ventilation. Architect James Ware designed the "dumbbell tenement"—shaped like a dumbbell from above, narrow in the middle with wider ends.
The air shaft solution: The narrow indentation created an "air shaft" between buildings, technically meeting legal requirements for windows and ventilation.
Why it failed: The shafts were only 5–6 feet wide, ran from ground to roof, and became garbage chutes and disease incubators. They trapped filth, blocked light, and created perfect conditions for disease.
From housing to infrastructure
19th-century cities were literally stinking, filthy places.
Thousands of pigs roamed city streets, eating garbage—and creating their own filth.
New York had an estimated 20,000+ pigs in the 1840s–1850s.
Cities in the 19th century depended entirely on horses for transportation and freight. Horses pulled streetcars, delivery wagons, carriages, and moved all urban goods.
The scale of the problem: New York had over 100,000 horses by the 1880s. Each horse produced 20–30 pounds of manure per day. That's over 2 million pounds of horse manure deposited in city streets every single day.
Where did it go? Streets, alleys, vacant lots, and rivers. Some was collected and sold to farmers, but most just accumulated. Street sweepers with water and brooms moved it around but didn't remove it. Flies and disease thrived in the manure.
Dead horses: Working horses had short lifespans. When they died in the streets (which happened constantly), they were often left to rot in place because removing a dead horse was expensive and difficult. In summer, the smell and fly problem became unbearable.
In the mid-1800s, thousands of pigs roamed city streets—especially in New York. They were seen as free garbage disposal because they ate organic waste dumped in streets and alleys.
Why people kept pigs: Poor immigrants (especially Irish) kept pigs for food. Pigs were valuable livestock that required no purchased feed—they ate garbage. For poor families, a pig represented significant economic value. Until the 1860s, cities had no regulations preventing people from keeping pigs.
The problems: Pigs created more filth than they consumed (they produced their own waste), spread disease, made streets dangerous and impassable, and concentrated waste rather than removing it. They also died in streets, creating more sanitation problems.
Class conflict: Efforts to remove pigs became a battle between poor people who depended on them for food and middle-class reformers who wanted "civilized" cities. Pig removal was about imposing middle-class standards of cleanliness and order on working-class neighborhoods. This wasn't just about health—it was about whose city it was and whose needs mattered. The pig controversy reveals how different groups understood urban space differently.
The Problems:
The Reality:
A sinecure is a job that requires little or no actual work but provides income and status—essentially a political favor or reward for loyalty.
In urban sanitation: Street cleaning jobs were often given as political appointments to reward supporters, not based on ability or willingness to actually do the work. Result: streets stayed filthy because workers didn't perform their duties.
Why this mattered: This corruption prevented effective sanitation even when systems existed on paper.
Plumbing and sewerage remained private responsibilities.
Americans resisted taxation and municipal regulation—even as cities became breeding grounds for epidemic disease.
Miasma theory held that disease was caused by "bad air" from rotting filth.
Even though their paradigm was incorrect, the solution would have mitigated disease had they actually followed through on their own theory.
Cleaning streets, improving drainage, and removing filth did reduce disease—just not for the reasons they thought.
From ancient times through the mid-1800s, most people believed disease was caused by "miasma"—bad air or poisonous vapors rising from rotting organic matter.
Core beliefs: Decay produces poisonous gases; vapors cause illness when inhaled; strong odors = dangerous miasma; night air especially dangerous because vapors settled near the ground overnight.
What they got right (accidentally): Cleaning streets, improving drainage, removing garbage, and building sewers did reduce disease—just not for the reasons people thought. It wasn't the bad air that was dangerous; it was the bacteria in the filth. By removing filth to eliminate "bad air," they were actually removing disease-causing microbes and breaking transmission pathways.
What they got wrong: Couldn't explain person-to-person transmission, couldn't identify disease-causing organisms, led to moral judgments about the sick (those who lived in "bad air" were seen as morally suspect), and sometimes led to counterproductive measures (avoiding night air rather than fixing sewers).
The transition to germ theory: By the 1880s–1890s, scientists like Louis Pasteur and Robert Koch were demonstrating that specific microorganisms caused specific diseases. This germ theory gradually replaced miasma theory, though many people held onto older beliefs well into the 20th century.
A Double-Edged Sword
Water-closets (indoor toilets) appeared slowly and unevenly:
A water-closet was an indoor toilet that used water to flush waste away. The term distinguished it from the outdoor privy or chamber pot.
Why slow adoption? Early water-closets were smelly (poor seals and ventilation), noisy (gurgling sounds), and difficult to clean. Many people preferred outdoor privies where odors stayed outside.
Status symbol: By mid-century, improved designs made water-closets more practical, but only middle- and upper-class families could afford them. Indoor plumbing became a class marker.
Between 1840–1870, cities built central waterworks:
Convenience, not hygiene, drove adoption. The connection between hygiene and disease was not understood.
Many homes had plumbing without connection to sewers:
Increased water usage created new problems:
"Modern" plumbing without sewers made cities more dangerous, not safer.
Sewer gas is a mixture of toxic gases (methane, hydrogen sulfide, ammonia) produced by decomposing sewage. Poorly designed pipes allowed these gases to leak into homes.
Why people feared it: They believed sewer gas itself caused disease (miasma theory). Wrong mechanism, but reasonable fear—sewer gas indicated sewage exposure, and sewage carried deadly bacteria.
The real danger: The gas didn't cause disease directly, but it signaled proximity to sewage that *did* carry cholera, typhoid, and dysentery bacteria.
By mid-century, American cities had:
Enter cholera—the disease that would force Americans to rethink everything.
Why did indoor plumbing initially make urban disease problems worse rather than better?
The Disease That Changed America
Cholera provides a lens for understanding the entire 19th century.
19th-century cholera = 14th-century plague
No evidence of cholera in the West before the 19th century.
Cholera became a pandemic disease because of 19th-century transportation improvements.
How cholera spread:
The irony: Technologies celebrated as "progress"—steamships, railroads, canals—also spread deadly disease faster than ever before. Modernity carried biological costs.
Three major outbreaks devastated American cities:
Cholera overwhelmed 19th-century cities:
Cholera killed 50-60% of those infected if untreated. Major outbreaks killed thousands in a matter of days.
Many Americans interpreted cholera in religious terms:
Governments proclaimed Days of Prayer and Fasting.
Cholera exposed the depth of poverty and misery in American cities.
Others drew the opposite conclusion:
Doctors in the 19th century were not highly respected:
Doctors were unable to prevent or cure cholera, further damaging medicine's reputation.
Medical schools needed bodies for anatomical study, but legal cadavers were scarce.
The practice: "Resurrectionists" dug up fresh graves and sold bodies. Nighttime grave raids targeted pauper and African American cemeteries especially.
Public outrage: Families guarded graves, cemeteries built watchtowers, scandals made international news. People believed doctors let patients die to obtain bodies.
Result: Deep public distrust of the medical profession.
Doctors relied on miasma theory and pre-disposing causes:
These treatments often harmed patients more than they helped.
With little faith in doctors, people turned to alternatives:
Epidemic created a booming market for dubious cures.
Why did some reformers argue that cholera revealed "man's injustice" rather than "God's justice"?
Public Health, Sewers, and the Fight Against Urban Disease
A revolutionary concept emerged in mid-19th century Britain:
Disease depends upon sanitation.
Role: British lawyer, social reformer, architect of modern public health
Influenced by: Jeremy Bentham, John Stuart Mill (utilitarian philosophy)
Key belief: Activist central government can solve social problems
His 1842 Report transformed public health forever.
The most famous epidemiological detective story in history.
Snow's famous map showed cholera deaths clustered around the Broad Street pump—early evidence of modern epidemiological methods
Sanitarians initially believed in miasma theory—disease from "bad air." But evidence was mounting that water, not air, spread cholera.
Sanitarians built water and sewer systems based on evidence of contamination—even before they understood bacteria.
American cities began their "sanitary awakening" in the mid-19th century.
New York City creates America's first coordinated response to epidemic disease.
Disease might not be curable, but it could be prevented through organized community effort.
Role: Sanitation engineer, reformer, NYC Street Cleaning Commissioner (1895–98)
Innovations:
"Cleanliness is a civic responsibility."
By the 1870s–1880s, American thinking shifted.
Clergy increasingly emphasized environmental causes of suffering, not just individual sin.
Paradigm: A worldview underlying the theories and methods of a scientific field
Government intervention becomes legitimate. Public health becomes a justification for regulation.
They got the mechanism wrong (miasma vs. germs) but the solutions right (clean water, sewers, sanitation).
The city could not survive without collective action.
Public health becomes:
The sanitary reform movement pioneered methods that would define Progressivism:
Next lecture: These urban experiments become a national movement.
Modern public health emerges not from compassion alone, but from fear, death, and necessity.
Urbanization made disease unavoidable—and reform unavoidable with it.
Government growth wasn't ideological—it was practical. Collective problems required collective solutions once cities became death traps.
The urban disease crisis forced Americans to accept that health was a public responsibility, not just a private matter.
This acceptance created the foundation for the modern regulatory state.
Modern government grew not from ideology alone, but from crisis and necessity.