Data Visualization and Cholera: An Unexpected Connection
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Data Visualization and Cholera: An Unexpected Connection

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Radial chart london cholera

Data Visualization and Cholera: An Unexpected Connection

Necessity is the mother of invention, and in the mid-1800s, understanding the spread of cholera was a matter of life and death.

Ruthless Efficiency

Cholera was a ruthlessly efficient killer, with both rapid onset and severe symptoms. By the time the disease made its way to London and New York in the early 1830s, hundreds of thousands of people had died across Europe, Africa, and Asia.

Not only our personal and national interests, […] it may be said without exaggeration, [that cholera] concerns the whole human race.

– Thomas Whiteside Hime

Needless to say, the human race was concerned. Thanks to high-speed printing press technology, daily newspaper circulations were rising dramatically, and this allowed journalists to experiment with new reporting techniques, including charting data.

cholera line chart

At the time, the chart above was such a novel approach that it required four paragraphs to explain how to read it. People of that era were simply not used to seeing data in a visual form. At a glance though, the chart is extremely effective at communicating a grim message: cholera had ravaged New York City over the summer of 1849.

Despite the concerted push to eradicate the disease, the medical community was still largely in the dark about how to prevent future outbreaks. Because doctors could treat numerous patients without falling ill, it was assumed that a miasmic environment (i.e. slums, densely-packed housing) was causing the spread.

Data Viz in the Time of Cholera

Today, we have tools that allow us to map just about anything, but in the mid-1800s, mapping data was still an innovative concept.

As early as the 1830s, geographers began using spatial analysis to study cholera epidemiology. The heat map below shows which sections of Paris were hardest hit by a recent outbreak of cholera.

1832 cholera map paris

In 1854, Dr. John Snow was convinced that cholera was spreading via tainted water and decided to display neighborhood mortality data directly on a map. This method clearly revealed a cluster of cases around a specific pump.

john snow cholera map
View the full version of the map here

The result is one of the most influential maps in modern history.

In addition to the real-world utility the map provided in helping physicians understand how cholera was spreading, it also exemplified a seismic shift in thinking that opened up new avenues for data to be analyzed and displayed.

Despite the tragic circumstances of the time period, we can be thankful that the urgency of the situation allowed the world’s pioneering researchers, journalists, and physicians to experiment with new data visualization techniques to better understand the world.

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Misc

Animated Map: Visualizing Earth’s Seasons

This map visualizes Earth’s seasons, showing how our planet’s Arctic sea ice and vegetation changes throughout the year.

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Animated Map: Visualizing Earth’s Seasons

Why does Earth have seasons?

Many people think the seasons are dictated by Earth’s proximity to the Sun, but this isn’t the case. It’s the Earth’s tilt, not its closeness to the Sun, that influences our seasons.

This animated map by Eleanor Lutz visualizes Earth’s seasons, showing how the temperature changes impact ice levels in the Arctic as well as vegetation more broadly. It also highlights the cloud cover and sunlight each hemisphere receives throughout the year, with each frame in the animation representing a month of time.

Why is Earth Tilted?

Unlike some of the planets that sit completely upright and rotate perpendicularly, Earth rotates on a 23.5-degree axis.

But why? A commonly accepted theory among the scientific community is the giant impact hypothesis. According to this theory, a celestial object called Theia collided with Earth many years ago, when the planet was still forming. This collision not only knocked Earth into its tilted position—some believe that the dust and debris from this impact ended up forming our moon.

Ever since, our planet has been rotating with a slight tilt (which itself is not fixed, as it “wobbles” in cycles), giving us our varying seasons throughout the year.

How Earth’s Tilt Influences our Seasons

As our planet orbits the Sun, it’s always leaning in the same direction. Because of its tilt, the different hemispheres receive varying amounts of sunlight at different times of the year.

In December, Earth is technically closer to the Sun than it is in June or July. However, because the Northern Hemisphere is tilted away from the Sun during December, that part of the planet experiences winter during that time.

Earth's Seasonal Climates

The graphic above by the Smithsonian Science Education Center (SSEC) visualizes Earth’s orbit throughout the year, showing when each hemisphere receives the most direct sunlight (and thus, experiences summer).

The Climate Change Impact

While our seasons have always varied, it’s worth noting that climate change has impacted our seasons, and changed how much Arctic ice we lose each summer.

In the past, millions of miles of ice remained frozen throughout the summer months. In the 1980s, there were 3.8 million square miles of ice in July—that’s roughly the same size as Australia.

Over the years, Arctic ice cover has steadily declined. In July 2020, the ice cover was only 2.8 million square miles—a million less than the amount four decades ago.

Some scientists are predicting that we could lose our summer sea ice entirely by 2035, which would have a devastating impact on the Artic’s wildlife and the indigenous people who live there.

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10 Travel Destinations for Post-Pandemic Life

Excited to get back to travelling the world? This infographic highlights the 10 most popular tourist destinations.

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10 Travel Destinations for Post-Pandemic Life

On March 11, 2020, the World Health Organization formally classified the COVID-19 outbreak as a pandemic. The resulting travel bans decimated the tourism industry, and international air travel initially fell by as much as 98%.

Almost two years later, travel is finally back on the table, though there are many restrictions to consider. Regardless, a survey conducted in September 2021 found that, as things revert to normalcy, 82% of Americans are looking forward to international travel more than anything else.

To give inspiration for your next vacation (whenever that may be), this infographic lists the 10 most visited countries in 2019, as well as three of their top attractions according to Google Maps.

Bon Voyage

Here were the 10 most popular travel destinations in 2019, measured by their number of international arrivals.

CountryNumber of international arrivals in 2019 (millions)
🇫🇷 France*90.0
🇪🇸 Spain83.5
🇺🇸 U.S.79.3
🇨🇳 China65.7
🇮🇹 Italy64.5
🇹🇷 Turkey51.2
🇲🇽 Mexico45.0
🇹🇭 Thailand39.8
🇩🇪 Germany39.6
🇬🇧 United Kingdom39.4

*Estimate | Source: World Bank

France was the most popular travel destination by a significant margin, and it’s easy to see why. The country is home to many of the world’s most renowned sights, including the Arc de Triomphe and Louvre Museum.

The Arc de Triomphe was built in the early 1800s, and honors those who died in the French Revolutionary and Napoleonic Wars. In 1944, Allied soldiers marched through the monument after Paris was liberated from the Nazis.

The Louvre Museum, on the other hand, is often recognized by its giant glass pyramid. The museum houses over 480,000 works of art, including Leonardo da Vinci’s Mona Lisa.

Art isn’t the only thing that France has to offer. The country has a reputation for culinary excellence, and is home to 632 Michelin-starred restaurants, the most out of any country. Japan comes in at second, with 413.

While You’re There…

After seeing the sights in Paris, you may want to consider a visit to Spain. The country is the southern neighbor of France and is known for its beautiful villages and beaches.

One of its most impressive sights is the Sagrada Familia, a massive 440,000 square feet church which began construction in 1882, and is still being worked on today (139 years in the making). The video below shows the structure’s striking evolution.

At a height of 172 meters, the Sagrada Familia is approximately 52 stories tall.

Another popular spot is Ibiza, an island off the coast of Spain that is famous for its robust nightlife scene. The island is frequently mentioned in pop culture—Netflix released an adventure/romance movie titled Ibiza in 2018, and the remix of Mike Posner’s song I Took a Pill in Ibiza has over 1.4 billion views on YouTube.

Beaches Galore

If you’re looking for something outside of Europe, consider Mexico or Thailand, which are the 7th and 8th most popular travel destinations. Both offer hot weather and an abundance of white sand beaches.

If you need even more convincing, check out these links:

Expect Turbulence

Under normal circumstances, hundreds of billions of dollars are spent each year by international tourists. According to the World Travel & Tourism Council (WTCC), this spending accounted for an impressive 10.4% of global GDP in 2019.

Travel restrictions introduced in 2020 dealt a serious blow to the industry, reducing its share of global GDP to 5.5%, and wiping out an estimated 62 million jobs. While the WTCC believes these jobs could return by 2022, the emerging Omicron variant has already prompted many countries to tighten restrictions once again.

To avoid headaches in the future, make sure you fully understand the rules and restrictions of where you’re heading.

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