The History of Pandemics
Pan·dem·ic /panˈdemik/ (of a disease) prevalent over a whole country or the world.
As humans have spread across the world, so have infectious diseases. Even in this modern era, outbreaks are nearly constant, though not every outbreak reaches pandemic level as COVID-19 has.
Today’s visualization outlines some of history’s most deadly pandemics, from the Antonine Plague to the current COVID-19 event.
A Timeline of Historical Pandemics
Disease and illnesses have plagued humanity since the earliest days, our mortal flaw. However, it was not until the marked shift to agrarian communities that the scale and spread of these diseases increased dramatically.
Widespread trade created new opportunities for human and animal interactions that sped up such epidemics. Malaria, tuberculosis, leprosy, influenza, smallpox, and others first appeared during these early years.
The more civilized humans became – with larger cities, more exotic trade routes, and increased contact with different populations of people, animals, and ecosystems – the more likely pandemics would occur.
Here are some of the major pandemics that have occurred over time:
|Name||Time period||Type / Pre-human host||Death toll|
|Antonine Plague||165-180||Believed to be either smallpox or measles||5M|
|Japanese smallpox epidemic||735-737||Variola major virus||1M|
|Plague of Justinian||541-542||Yersinia pestis bacteria / Rats, fleas||30-50M|
|Black Death||1347-1351||Yersinia pestis bacteria / Rats, fleas||200M|
|New World Smallpox Outbreak||1520 – onwards||Variola major virus||56M|
|Great Plague of London||1665||Yersinia pestis bacteria / Rats, fleas||100,000|
|Italian plague||1629-1631||Yersinia pestis bacteria / Rats, fleas||1M|
|Cholera Pandemics 1-6||1817-1923||V. cholerae bacteria||1M+|
|Third Plague||1885||Yersinia pestis bacteria / Rats, fleas||12M (China and India)|
|Yellow Fever||Late 1800s||Virus / Mosquitoes||100,000-150,000 (U.S.)|
|Russian Flu||1889-1890||Believed to be H2N2 (avian origin)||1M|
|Spanish Flu||1918-1919||H1N1 virus / Pigs||40-50M|
|Asian Flu||1957-1958||H2N2 virus||1.1M|
|Hong Kong Flu||1968-1970||H3N2 virus||1M|
|HIV/AIDS||1981-present||Virus / Chimpanzees||25-35M|
|Swine Flu||2009-2010||H1N1 virus / Pigs||200,000|
|SARS||2002-2003||Coronavirus / Bats, Civets||770|
|Ebola||2014-2016||Ebolavirus / Wild animals||11,000|
|MERS||2015-Present||Coronavirus / Bats, camels||850|
|COVID-19||2019-Present||Coronavirus – Unknown (possibly pangolins)||848K (Johns Hopkins University estimate as of 10:28am PT, Aug 31, 2020)|
Despite the persistence of disease and pandemics throughout history, there’s one consistent trend over time – a gradual reduction in the death rate. Healthcare improvements and understanding the factors that incubate pandemics have been powerful tools in mitigating their impact.
Wrath of the Gods
In many ancient societies, people believed that spirits and gods inflicted disease and destruction upon those that deserved their wrath. This unscientific perception often led to disastrous responses that resulted in the deaths of thousands, if not millions.
In the case of Justinian’s plague, the Byzantine historian Procopius of Caesarea traced the origins of the plague (the Yersinia pestis bacteria) to China and northeast India, via land and sea trade routes to Egypt where it entered the Byzantine Empire through Mediterranean ports.
Despite his apparent knowledge of the role geography and trade played in this spread, Procopius laid blame for the outbreak on the Emperor Justinian, declaring him to be either a devil, or invoking God’s punishment for his evil ways. Some historians found that this event could have dashed Emperor Justinian’s efforts to reunite the Western and Eastern remnants of the Roman Empire, and marked the beginning of the Dark Ages.
Luckily, humanity’s understanding of the causes of disease has improved, and this is resulting in a drastic improvement in the response to modern pandemics, albeit slow and incomplete.
The practice of quarantine began during the 14th century, in an effort to protect coastal cities from plague epidemics. Cautious port authorities required ships arriving in Venice from infected ports to sit at anchor for 40 days before landing — the origin of the word quarantine from the Italian “quaranta giorni”, or 40 days.
One of the first instances of relying on geography and statistical analysis was in mid-19th century London, during a cholera outbreak. In 1854, Dr. John Snow came to the conclusion that cholera was spreading via tainted water and decided to display neighborhood mortality data directly on a map. This method revealed a cluster of cases around a specific pump from which people were drawing their water from.
While the interactions created through trade and urban life play a pivotal role, it is also the virulent nature of particular diseases that indicate the trajectory of a pandemic.
Scientists use a basic measure to track the infectiousness of a disease called the reproduction number — also known as R0 or “R naught.” This number tells us how many susceptible people, on average, each sick person will in turn infect.
Measles tops the list, being the most contagious with a R0 range of 12-18. This means a single person can infect, on average, 12 to 18 people in an unvaccinated population.
While measles may be the most virulent, vaccination efforts and herd immunity can curb its spread. The more people are immune to a disease, the less likely it is to proliferate, making vaccinations critical to prevent the resurgence of known and treatable diseases.
It’s hard to calculate and forecast the true impact of COVID-19, as the outbreak is still ongoing and researchers are still learning about this new form of coronavirus.
Urbanization and the Spread of Disease
We arrive at where we began, with rising global connections and interactions as a driving force behind pandemics. From small hunting and gathering tribes to the metropolis, humanity’s reliance on one another has also sparked opportunities for disease to spread.
Urbanization in the developing world is bringing more and more rural residents into denser neighborhoods, while population increases are putting greater pressure on the environment. At the same time, passenger air traffic nearly doubled in the past decade. These macro trends are having a profound impact on the spread of infectious disease.
As organizations and governments around the world ask for citizens to practice social distancing to help reduce the rate of infection, the digital world is allowing people to maintain connections and commerce like never before.
Editor’s Note: The COVID-19 pandemic is in its early stages and it is obviously impossible to predict its future impact. This post and infographic are meant to provide historical context, and we will continue to update it as time goes on to maintain its accuracy.
Update (March 15, 2020): We’ve adjusted the death toll for COVID-19, and will continue to update on a regular basis.
Visualized: The World Leaders In Positions of Power (1970-Today)
Who has led the world’s 15 most powerful countries over the last 50 years? This visual looks at world leaders from 1970 to today.
Visualized: The World Leaders In Positions of Power
Who were the world leaders when the Berlin Wall fell? How many women have been heads of state in prominent governments? And who are the newest additions to the list of world leaders?
This graphic reveals the leaders of the most influential global powers since 1970. Countries were selected based on the 2020 Most Powerful Countries ranking from the U.S. News & World Report.
Note: Switzerland has been omitted due to the swiftly changing nature of their national leadership.
The 1970s: Economic Revolutions
Our graphic starts in 1970, a year in which Leonid Brezhnev ruled the Soviet Union, while on the other side of the Iron Curtain, Willy Brandt was presiding over West Germany.
In the U.S., Richard Nixon implemented a series of economic shocks to stimulate the economy, but resigned in scandal due to the Watergate tapes in 1974. In the same time period, China was undergoing rapid industrialization and economic hardship under the final years of rule of communist revolutionary Mao Zedong, until his death in 1976.
In 1975, the King of Saudi Arabia, Faisal bin Abdulaziz Al Saud was assassinated by his nephew. The decade also marked the end of Park Chung-Hee’s dictatorship in South Korea when he was assassinated in 1979.
To cap off the decade, Margaret Thatcher became the first female prime minister of the United Kingdom in 1979, transforming the British economy using a laissez-faire economic policy that would come to be known as Thatcherism.
The 1980s: Reaganomics and the Fall of the Wall
The 1980s saw Ronald Reagan elected in the U.S., beginning an era of deregulation and economic growth. Reagan would actually meet the Soviet Union’s president, Mikhail Gorbachev in 1985 to discuss human rights and nuclear arms control amid the tensions of the Cold War.
The 1984 assassination of the Indian prime minister, Indira Gandhi was also a defining event of the decade. She was succeeded by her son, Rajiv Gandhi for only seven years before his own assassination in 1991.
The ‘80s were clearly turbulent times for world leaders, especially towards the end of the decade. In 1989, the Berlin Wall fell and Germany was reunified under chancellor Helmut Kohl. 1989 was also the year when the devastating events occurred at the Tiananmen Square protests in China, under president Deng Xiaoping. The event left a lasting mark on China’s history and politics.
The 1990s: War 2.0 and the Promise of the EU
The beginning of a new decade marked the end of the Cold War and the fall of the Soviet Union, leading to Boris Yeltsin’s position as the first president of the Russian Federation. A sense of peace, or at least the knowledge that a finger wasn’t floating above a nuclear launch button at any given moment, brought a sense of global calm.
However, this does not mean the decade was without conflict. The Gulf War began in 1990, led by the U.S. military’s Commander-in-Chief George H.W. Bush. In the mid-90s, prime minister Yitzhak Rabin of Israel was assassinated by Jewish extremists.
In spite of this, the ‘90s were a time of optimism for many. In 1993, the European project began. The European Union was founded with the support European leaders like the UK’s prime minister John Major, France’s president Francois Mitterrand, and chancellor Helmut Kohl of Germany.
The 2000s: Historic Firsts and Power Shifts
The dawn of a new century had people feeling both hopeful and scared. While Y2K didn’t end the world, many transformative events did occur, such as the 9/11 attacks in New York and the subsequent war on terror led by U.S. president George W. Bush.
On the other hand, Angela Merkel made history becoming the first female chancellor of Germany in 2005. A few years later, Barack Obama also achieved a momentous ‘first’ as the first African-American president in the United States.
The 2000s to early 2010s also revealed rapidly changing power shifts in Japan. Shinzō Abe rose to power in 2006, and after five leadership changes in seven years, he eventually circled back, ending up as prime minister again by 2013—a position he held until late 2020.
|Country||Number of Leaders Since 1970|
|🇰🇷 South Korea||10|
|🇸🇦 Saudi Arabia||5|
The 2010s: World Leaders Face Uncertainty
The 2010s were more than eventful. The Hong Kong protests under Chinese president Xi Jinping, and the annexation of Crimea led by Vladimir Putin, uncovered the wavering dominance of democracy and international law.
UK Prime Minister David Cameron’s move to introduce a Brexit referendum, resulted in just over half of the British population voting to leave the EU in 2016. This vote led to a rising feeling of protectionism and a shift away from globalization and multilateral cooperation.
Donald Trump’s U.S. presidential election was a shocking political longshot in the same year. Trump’s stint as president will likely have a longstanding impact on the course of American politics.
Two countries elected their first female leaders in this decade: president Park Geun-Hye in South Korea, and prime minister Julia Gillard in Australia. Here’s a look at which global powers have been led by women in the last 50 years.
|🇦🇺 Australia||Julia Gillard|
|🇨🇦 Canada||Kim Campbell|
|🇩🇪 Germany||Angela Merkel|
|🇮🇳 India||Indira Gandhi|
|🇰🇷 South Korea||Park Geun-Hye|
|🇹🇷 Turkey||Tansu Ciller|
|🇬🇧 UK||Margaret Thatcher|
|🇬🇧 UK||Theresa May|
2020 to Today
No one can avoid talking about 2020 without talking about COVID-19. Many world leaders have been praised for their positive handling of the pandemic, such as Angela Merkel in Germany. Others on the other hand, like Boris Johnson, have received critiques for slow responses and mismanagement.
The year 2020 packed about as much punch on its own as an entire decade does, from geopolitical tensions to a nail-biting 2020 U.S. election. The world is on high alert as the now twice-impeached Trump prepares his transfer of power following the riot at the U.S. Capitol.
The newest addition to the ranks of world leaders, Joe Biden, has recently taken his place as the 46th president of the United States on January 20, 2021.
Editor’s note: We’ll continue to update this graphic on world leaders as time goes on. Unfortunately, we were unable to include world leaders from more countries, as we were limited by the graphic format and user experience.
U.S. Presidential Voting History from 1976-2020 (Animated Map)
With this map of U.S. presidential voting history by state, discover patterns that have emerged over the last twelve elections.
U.S. Presidential Voting History by State
After a tumultuous election, all states have now certified their 2020 presidential voting results. Which states changed party allegiance, and how do the results compare to previous years?
Note: this post has been updated on January 19, 2021 to reflect the latest data.
Each State’s Winning Party
To calculate the winning ratio, we divided the votes for the state’s winning party by the total number of state votes. Here’s another look at the same data, visualized in a different way.
This graphic was inspired by this Reddit post.
As the voting history shows, some states—such as Alaska, Oklahoma, and Wyoming—have consistently supported the Republican Party. On the other hand, Hawaii, Minnesota, and the District of Columbia have been Democrat strongholds for many decades.
The District of Columbia (D.C.) is a federal district, and is not part of any U.S. State. Its population is urban and has a large percentage of Black and college-educated citizens, all of which are groups that tend to identify as Democrat.
Swing states typically see a close contest between Democrats and Republicans. For example, Florida’s average margin of victory for presidential candidates has been just 2.7% since 1996. It’s often seen as a key battleground, and for good reason: the state has 29 electoral college votes, meaning it has a high weighting in the final outcome.
Memorable Election Years
Within U.S. presidential voting history, some election results stand out more than others. In 1984, President Reagan was re-elected in a landslide victory, winning 49 out of 50 states. The remarkable win has been credited to the economic recovery during Reagan’s first term, Reagan’s charisma, and voters’ opposition to the Democrat’s planned tax increases.
In 1992, self-made Texas billionaire Ross Perot ran as a third-party candidate. He captured almost 19% of the popular vote, the highest percentage of any third-party presidential candidate in over 80 years. While he gained support from those looking for a change from traditional party politics, Bill Clinton ultimately went on to win the election.
Most recently, the 2020 election had a record voter turnout, with 66.3% of the eligible population casting a ballot. There was also a record number of mail-in ballots due to the COVID-19 pandemic. This led to widespread allegations of voter fraud, with President Trump and his allies filing 62 lawsuits seeking to overturn election results. In the end, 61 of the lawsuits were defeated and congress confirmed Joe Biden’s victory.
Voting History of Swing States
Both Trump and Biden focused on battleground states in 2020, but where were they successful? Here are nine of the swing states, and their voting history over the last two elections.
|2020 Winning Ratio||2020 Margin of Victory||2016 Winning Ratio||2016 Margin of Victory|
|Arizona||49.4% Democrat||0.31%||48.7% Republican||3.60%|
|Florida||51.2% Republican||3.36%||49.0% Republican||1.20%|
|Georgia||49.5% Democrat||0.24%||50.8% Republican||5.20%|
|Iowa||53.2% Republican||8.20%||51.2% Republican||9.40%|
|Michigan||50.6% Democrat||2.78%||47.5% Republican||0.20%|
|North Carolina||50.1% Republican||1.35%||49.8% Republican||3.60%|
|Ohio||53.3% Republican||8.03%||51.7% Republican||8.10%|
|Pennsylvania||50.0% Democrat||1.16%||48.9% Republican||0.70%|
|Wisconsin||49.5% Democrat||0.63%||47.2% Republican||0.70%|
The Republican party won four of the swing states in 2020, including Florida. However, 2020 was the first year since 1964 that the candidate who won Florida did not go on to win the election.
Five of the states—Arizona, Georgia, Michigan, Pennsylvania, and Wisconsin—flipped allegiance to the Democrats. In Georgia, the margin of victory was as small as 0.24% or about 12,000 votes. Ultimately, winning over these states helped lead to a Biden victory.
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