Major U.S. Epidemics

Updated September 13, 2021 | Logan Chamberlain

Here's a list of the major outbreaks in U.S history

Major disease outbreaks have shaped a lot of world history. When the Black Death pandemic swept through Europe and Asia, it fundamentally changed how people related to their faith, their employers, and their government. Disease has (if you'll forgive the pun) plagued societies for millennia, and the United State is no exception.

Take me to the Timeline

Take me to the Coronavirus (COVID-19)

Some useful terms

A lot of people are concerned about the definition of epidemic, and how it differs from a pandemic. An epidemic is when an infectious disease has spread rapidly through a community. An epidemic disease like cholera, measles, or influenza will crop up and spread across a geographic area, infecting a large number of people.

A pandemic is an epidemic that spreads beyond individual communities to affect large parts of the world. Neither the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have any hard numbers to distinguish an epidemic vs. pandemic. E.g. there isn't a threshold number of cases of a disease that tips it into "pandemic" territory. After the outbreak of a disease spreads beyond a geographical area, epidemiologists (people who study the spread of disease) will make a judgement call.

Disease vectors, and other ways to get sick

Infectious diseases spread in a variety of ways. How they spread plays a big part of how, when, where, and why we have different disease outbreaks. The three most-discussed are vector-borne diseases, which are carried and spread by living things, airborne diseases, and waterborne diseases. There are also sexually-transmitted infections and foodborne illnesses, but these aren't as likely to reach epidemic proportions. 

Any diseases that are mentioned in the timeline can also be found in our encyclopedia, which will give you details about how it spreads.

Zika virus and other global epidemics

We've limited the scope of this article to diseases that had epidemic outbreaks in the United States, which might exclude some diseases that are epidemics elsewhere. That might even exclude some diseases that came to the United States as the result of an epidemic, like the Zika virus or Ebola.

Timeline: Major Epidemics in the U.S.

Read about the major disease outbreaks that have shaped American history; from cholera to measles, from Spanish Flu to polio, and from AIDS to the novel coronavirus/COVID-19.

1616 –

  • During the very earliest days of colonial contact in New England, disease swept the Northeast. European fishermen, while sailing along the coast or interacting with locals, carried European diseases that devastated the region. Anywhere between 30% and 90% of the local population died, possibly from leptospirosis.

1713 –

  • Early American cities and towns had poor health infrastructure, poor public sanitation, and little to no measures to control the spread of disease. As the Colonies grew bigger, there was more grounds for infection to spread. There were several outbreaks of smallpox, measles, and influenza that spread throughout major cities like New York and Boston. 

1793 –

  • Starting in 1793, the city of Philadelphia (already one of the largest and most influential cities in America) suffered a massive outbreak of yellow fever. Up to 5,000 people died from the disease out of a total population of 50,000. On top of the deaths, up to 20,000 people fled. The epidemic spread to other cities. Despite the immense cost, American cities continued to grow during this time. City officials responded by limiting access to rivers, where the disease spread most, causing more inland development.

1820 –

  • After fading from the public eye for a while, yellow fever sweeps the South. Yellow fever is believed to originate from Africa, and is carried by several types of mosquito. The 1820 epidemic hits Savannah, Georgia the hardest. Savannah, one of the largest slave ports in the country, likely brought over mosquitoes carrying the disease.

1832 –

  • After the initial boom in industry, larger numbers of people started moving into the cities. At this period of time there weren't comprehensive sewer systems, nor were people aware of germs. The sudden increase in population overwhelmed city sanitation. The biggest problem was human waste getting in the water supply, which causes cholera. The disease would become a constant presence in dirtier parts of town. Over 10,000 people died in New York, and over 4,000 died in New Orleans. 

1841 –

  • Yellow fever spreads across the South once again, with at least three major disease outbreaks. During this period of time, there are at least 20 outbreaks across the Americas.


  • The port of New Orleans, which has high humidity and conditions good for mosquito breeding, sees a sudden increase in cases of yellow fever. At least 10,000 die from the disease.

Sept. 13, 1759

  • Over 13,000 people died from yellow fever in lower Mississippi Valley; people living along the river are especially susceptible to the illness.

1898 –


  • Yellow fever becomes a major problem for the U.S. military and America's empire; Cuba, which the United States recently conquered and took from Spanish control, has dangerously high rates of the disease. So does Panama, where President Roosevelt is trying to build his Canal. The United States adopts the ideas of Cuban doctor Carlos Finlay and American Army doctor Walter Reed. They believe that mosquitoes spread the disease.

1904 – 1906

  • The U.S. Army starts implementing public health measures like putting up mosquito nets. Through a concerted effort, they are able to nearly eradicate mosquito-borne illnesses from Panama and Cuba. Other groups would go on to perform similar projects in Brazil and Mexico.


  • Over 7,000 deaths occurred and 27,363 cases were reported of polio in America's worst polio epidemic. One of the biggest centers of the disease was in Brooklyn, which accounted for over 2,000 of the deaths. The fear of polio, combined with little understanding of how it spread (due to feces in food or water, like in an ill-maintained pool) caused a mass panic. People who could afford to abandoned cities in droves until the epidemic ended.

1917 –


  • The origin point is disputed, but it is assumed by historians that the "Spanish Flu," or the first influenza pandemic involving the virus h2N1, began in 1917. Despite the name, it is widely agreed that it did not originate in Spain. The two most likely origins are the United States or China. There is evidence that the population in China might have already had some immunity to the flu, and there is evidence that the United States experienced cases well before the influenza outbreak in Europe.

January – March 1918

  • U.S. health officials in Kansas note a disease spreading in several military camps where troops are training for deployment to Europe. Little is done to contain the disease and it spread across the country.

August – November 1918

  • A strain of influenza appears in Boston, MA, as well as in a military camp in Brest, France, and in Freetown, Sierra Leone. Due to the poor sanitation and the tight quarters, the flu spreads like wildfire through the troops. When they are sent home from their deployments, the soldiers bring the highly infectious flu home with them. Most regional newspapers suppress news of the disease to keep up morale during WWI; Spain, a neutral country, does not suppress the news, leading people to believe it began there.

1919 – 1920

  • There are wildly conflicting estimates about how many people caught the flu and how many people died from it. The lack of records from the time (either due to wartime censorship or shortages) makes it hard to tell. The smallest estimate is that 17 million people died. The highest estimate is that 100 million people died, or 5% of the global population. The flu pandemic is believed to have infected 500 million people, or over a quarter of the world.

1949 –

  • Over 6,000 people die from polio in the United States, out of a reported 100,000 cases. This, followed by the development of the polio vaccine, prompts one of the first major drives to inoculate children in the U.S.


  • The "Asian Flu," H2N2, comes to the united states from China. It originates from a mutant flu strain carried by ducks. It arrives in the U.S. in June. This influenza pandemic kills 116,000 people in the United States.


  • The "Hong Kong Flu" is the third of the three influenza pandemics of the 1900s. This flu had a much lower mortality rate than the other two, but still resulted in 33,000 deaths in the U.S.

1981 –


  • The CDC identifies a new disease in five U.S. citizens. Later studies conclude that the disease probably first appeared in Africa in the 1960s, and came to the United States in the 1970s. At this point the CDC has no name for the disease. Some people call it "junkie flu" since it affects many people who inject drugs.


  • Several retroviruses discovered across the country are confirmed to be a single disease, which will go on to be named HIV.


  • HIV/AIDS spreads across the country, especially infecting high rates of LGBT people, lower income people, and drug addicts. For a while, AIDS is also known as GRID ("Gay-Related Immune Deficiency"). It's also called "4H" disease since it affects "Hemophiliacs, Heroin Addicts, Homosexuals, and Haitians". Treatment for the disease receives little funding and attention due to the groups it affects. AZT, the first treatment to delay the onset of AIDS, is released in 1987.


  • Many high-profile celebrities, including Eazy-E and Freddie Mercury, die of AIDS. Other living celebrities, like Magic Johnson, come forward with the disease. New treatments for the disease become available, and there is a major cultural shift in how people approach safety during sex. The rate of infection in the U.S. drops off.


  • The FDA approves new tests that can quickly detect HIV, and new treatments. In 2007, Timothy Ray Brown becomes the first man cured of HIV. By this time, at least 600,000 people have died of HIV/AIDS in the U.S. alone.


  • One of Milwaukee's water treatment plants became contaminated with cryptosporidium and killed more than 100; 403,000 cases reported.


  • in April, h2N1, also known as Swine Flu, broke out and quickly spread to more than 150 countries. The CDC reported that between April and October, 22 million Americans had contracted the virus, 98,000 required hospitalization, and about 3,900 people died from h2N1-related causes. The WHO estimated that the final death toll worldwide ending up reaching nearly 300,000.


January 11 – January 23

  • A new coronavirus, identified just as the novel coronavirus, claims its first official victim in China. Health officials implement strict quarantine conditions on the city. At least one American traveler returning from Wuhan contracts the disease before the city is isolated.

January 30

  • In response to the growing number of cases in Wuhan, the World Health Organization (WHO) declares the novel coronavirus outbreak a public health emergency.

January 31 – February 28

  • The number of cases of coronavirus continue to grow in Wuhan, and large numbers of people contract the disease in Italy, Iran, and South Korea. People worldwide are cautioned to prepare for the public health crisis to spread.

February 29

  • The coronavirus outbreak reaches the United States; the first victim dies to the disease in the U.S., prompting widespread panic.

March 3

  • The CDC lifts any restrictions on testing for coronavirus, now more accurately identified as COVID-19 (the disease caused by the coronavirus). The country begins efforts to improve testing capabilities after an initial shortage of tests.

March 11-13

  • The coronavirus outbreak in the U.S. is officially declared a national emergency. The Director-General of the WHO, Tedros Adhanom Ghebreyesus, declares the disease to have grown from epidemic proportions to a pandemic. At the urging of health officials, different states begin enforcing restrictions on businesses and public gatherings to contain the disease.
Sources +