1

World War II (1939–1945)

American veteran soldiers are entitled to several benefits as recognition for their service on behalf of the country, but this was not always the case. Before 1944, war veterans received pensions and disability-related medical care, but that was it. WWI veterans had received bonuses for their service, but these were not redeemable until 1945, which led to protests and turmoil during the Great Depression.

To avoid a similar situation with soldiers serving in WWII, a set of laws, popularly known as the "G.I. Bill", was passed in 1944. These laws guaranteed that, in addition to pensions and medical assistance, veterans were entitled to financial help towards education or training, low-cost loans, unemployment benefits, and job-search assistance . Since then, additional "G.I. Bills" have been passed, ensuring that veterans are looked after once their service is complete.

2

The Great Depression (1929–1939)

Historians agree that, despite President Roosevelt’s best efforts, the Great Depression was effectively ended by the industrial mobilization caused by WWII. America’s biggest economic crisis to date had been brought on by several factors , many of them related to reckless market speculation, inefficient monetary policies, lack of social security, and massive bank withdrawals made by panicked citizens.

While F.D.R.’s "New Deal" policies were insufficient to overcome the crisis, they successfully set up a system to prevent a similar economic collapse in the future . As a result of financial and banking reform, personal accounts were federally insured —which prevented future massive withdrawals that would deplete savings, commercial and investment banking were separated, and commissions were set up to regulate trading and prevent fraud. Additionally, social and welfare laws established pensions, work insurance, and unemployment compensation, and protected unions that allowed workers to collectively bargain with their employers.

3

The Great Chicago Fire (1871)

On October 8, 1871, a fire started on DeKoven Street, Chicago, and it burned for three days, destroying 17,450 buildings and leaving 300 casualties and thousands of people homeless. According to legend, the fire was started by a cow (owned by a woman named Mrs. O’Leary), although this was never confirmed; it was the wooden buildings, the strong wind, and the dry weather that turned an accident into a catastrophe.

Americans from all over the country rallied behind the relief effort, donating money, food, clothing, and more, but the tragedy also forced authorities to review their own municipal safety codes. New fire and building safety codes were implemented, banning wood buildings and requiring fire-safe materials such as brick, stone, or marble, as well as fireproof staircases, exit signs, and outward-opening doors. A new fire academy was founded to properly train firefighters, which put Chicago at the lead of America’s firefighting force.

4

Yellow Fever (1793)

In 1793, the city of Philadelphia received cargo ships from Saint-Domingue (modern-day Haiti), and with them, an epidemic that lasted for half a year. Among the cargo from the Caribbean, there were yellow fever-carrying mosquitoes, which thrived in the crowded docks and in the humid spring and summer weather. The open sewers, poor waste management, and general ignorance about the disease worsened the situation, which only let up with the cold fall weather, with 5,000 people, about 10% of the population, as casualties.

Although the widely believed cause of the spread of the epidemic —foul "miasma" or bad air— was incorrect, it did lead to proper infrastructure changes to prevent a similar situation. The city targeted polluted waterways and rotten waste, exposing severely contaminated wells. Municipal water systems to provide clean drinking water were created, and paved streets with proper gutters and sewers reduced the amount of stagnant water . Additionally, the crisis led to the establishment of municipal health boards, proper quarantine facilities for incoming ships, and municipal hospitals all across the country.

5

The Triangle Shirtwaist Factory Fire (1911)

Nowadays we expect any factory or building to have proper fire and safety systems in place, but not so long ago safe working conditions were not a given. Places like the Triangle Shirtwaist Factory in New York not only lacked fire alarms, sprinklers, and fire escapes, but also locked their doors during work hours to prevent unauthorized breaks and workers' union gatherings . On March 25, 1911, when a pile of rags caught fire, the single fire escape collapsed and, with firefighters' ladders only able to reach six of the ten floors, the factory became a deadly trap that took the lives of 146 workers.

New Yorkers were outraged by the conditions that led to the tragedy, and public pressure led to the establishment of an investigating commission. As a result, more than 30 safety laws were passed , making fire drills, sprinklers, fire escapes, and emergency exits mandatory, among other measures, all of which set a precedent for federal safety codes and protections. The event also strengthened labor unions all across the country, who pushed for better working conditions.

6

The Dust Bowl (1930s)

The 1929 Wall Street Crash had already kickstarted the Great Depression, but the American crisis was still deepening. By the start of the 1930s, years of severe drought had hit the Great Plains (comprising ten states in the Midwest and Rocky Mountain regions) and had worsened an environment already depleted by human intervention. Native grasses that protected the topsoil had been eradicated through plowing, leaving the land vulnerable to wind erosion, while intensive cultivation of single crops had depleted the land. All this caused severe dust storms that hit the plains, further eroding the fields and suffocating the crops. In an agricultural recession, thousands of families migrated West looking for work.

The government’s response had diverse approaches. The Soil Conservation Service focused on changing detrimental agricultural practices through educating farmers on contour plowing, crop rotation, and shelterbelt tree planting. FDR’s "New Deal" plan established subsidies for farmers, requiring landowners to distribute a percentage of the subsidy to their laborers, and thousands of cattle were acquired, butchered, and distributed by the government to the affected population. Ultimately, the return of rain in the 1940s ended the drought and helped restore the soil, but the education, conservation, and relief mechanisms implemented by the government ensured that the Great Plains would not be as severely affected by drought in the future.

7

The Cold War (1945-1991)

The euphoria of the WWII victory in American politics was short-lived, as the climate quickly shifted to a new threat: communism. The Cold War deeply affected domestic American life, and the paranoia of the Red Scare prompted the government to invest thousands of dollars in defense , infrastructure, political propaganda, and counter-espionage. Sadly, this paranoia also allowed government officials and politicians, like Senator Joseph McCarthy, to persecute and blacklist thousands of suspected communist sympathizers without solid evidence.

While the desire to beat the USSR in public achievements resulted in the government funding the military industry, science education and research, and sports programs, espionage and propaganda were targeted through the creation of federal agencies —among them the CIA, the NSC, and the NSA— that managed domestic security, international intelligence, information, and propaganda.

8

The Revolutionary War Smallpox Epidemic (1775–1782)

The 1775 North American Smallpox epidemic lasted for nearly a decade, well beyond the Revolutionary War, but the military leaders of the Revolution were the ones to put in the efforts to contain it and prevent further spreading of the disease. In 1775, smallpox was a rampant disease in the American colonies, and a big part of the population had not been exposed to it due to isolation. This meant that, when colonists from rural areas joined the Continental Army, overcrowded military camps became a hotspot of contagion. It is estimated that smallpox caused more casualties than the fighting itself.

While smallpox decimated the Revolutionary Army, the British, who had been traditionally exposed to the disease, were immune to it. Recognizing the need to stop the spread of the disease, George Washington ordered a secret mass immunization of the troops in 1777 , a measure that drastically lowered the mortality rates among the army. While several founding fathers were in favor of mass inoculations and better public health policies, most of the colonists were distrustful of vaccinations and of government-mandated health policies. The success of Washington’s mass inoculation showed that public health policies could make the difference, and paved the way for later policies and health systems.

9

The Cholera Waves (1832–1866)

The U.S. went through three major cholera waves in 1832, 1849, and 1866, with tens of thousands of casualties, economic crises, and mass panic. Rapidly growing cities lacked proper sewage, and rancid water accumulated in the unpaved streets, while overcrowding and poor living conditions furthered the contagion. New travel methods such as the railroad helped introduce the disease to different regions, while doctors blamed the epidemic on "bad air" or a divine punishment.

It was not until the 1866 wave that city governments decided to change their approach to the health crisis. New York was the first city to establish a Metropolitan Board of Health, which focused on improving sanitary conditions and reforming the hospital system. Police forces encouraged (or forced) residents to clean their yards and remove manure and rotten waste, while the city strived to maintain clean streets and build sewage systems. By the time the third cholera wave hit New York, the city was prepared, and the number of casualties was much lower. Following its example, other major cities established their own permanent boards of health, implemented municipal health codes, improved their hospitals, and constructed underground sewers.

10

The Smoking and Lung Cancer Crisis (1960s)

Although tobacco had been popular for decades, the 20th century saw a rise in consumption thanks to aggressive cigarette marketing campaigns in print, radio and television. Smoking was allowed everywhere, and it was portrayed as stylish and smart in movies and magazines. There was a lack of education about the addictive properties of nicotine and the chemicals present in commercial cigarettes , a fact that the tobacco industry was eager to keep concealed. By the 1960s, lung cancer and heart disease numbers had risen dramatically, forcing the government to address the situation.

The 1964 Surgeon General’s report was the first to publicly link lung cancer and heart disease with tobacco consumption. Following several reports by other specialists , public opinion about cigarettes drastically shifted, despite the efforts of the tobacco industry . In 1965, Congress passed a law requiring mandatory health warning labels on cigarette packaging, and in 1971, cigarette radio and TV ads were outlawed. As a result, from the 1960s to the 2010s, cigarette consumption decreased by nearly 50%.

11

The Pure Food and Drugs Act (1906)

If you are the kind of person who religiously scans the ingredient list on food and medicine labels, you might not know that these labels exist thanks to a novel (and several journalists' investigations). In the late 19th century, increased food and medicine demands led manufacturers to sell tainted or unsafe products with false labels and filled with unsafe preservatives. Factory sanitary conditions were also subpar, which led many journalists to write about the issue. In 1906, Upton Sinclair’s novel The Jungle described the meat-packing industry practices in a graphic and revolting way, which caused mass outrage.

The Pure Food and Drugs Act of 1906 was the first of a series of laws passed by Congress to address the issue. It created a federal agency (now called the FDA) responsible for overseeing food and drug manufacturing , banned a series of commonly used substances and active ingredients, outlawed the sale of spoiled or contaminated food, set an inspection system for factories, and acted as a baseline for future consumer protection laws.

1

What are bills made of?

Unlike other currencies, dollar bills are not made of paper or plastic. U.S. dollar bills are made from a special fabric blend composed of 75% cotton and 25% linen. This mix makes the bills extremely durable and resistant, and they can be folded about 4000 times before tearing.

2

What bills are valid?

Any U.S. dollar bill that was legally printed is valid, no matter how old, as American currency does not have an expiration date. While some bills might not be accepted by businesses of foreign exchange services due to their condition or if they are a discontinued version of the bill, the bills themselves are still valid, and American banks will accept them, though they might take them out of circulation.

3

American leaders

Five bills have a depiction of an American president. The exceptions are the $10 bill, with Alexander Hamilton on the front, and the $100 bill, with Benjamin Franklin. The $1 bill, depicting George Washington, is extremely symbolic: several elements are repeated 13 times as a nod to the thirteen colonies, and it showcases the Bald Eagle and the Eye of Providence as a sign of God watching over America.

4

A change in size

Did you know that dollar bills used to be so big that they were nicknamed "horse blankets"? Original dollar bills were 7.4 × 3.1 inches. In 1929, the Treasury Department reduced the size of bills to 6.14 × 2.61 inches to reduce production costs and materials. Old bills, though still valid, are worth much more as collector items.

5

Uniformity

Besides their value and design, all dollar bills have the same size (6.14 × 2.61 inches), color, and weight (1 gram) , which sets American currency apart from other countries where bills of different values are differentiated by size, color, or both. Why doesn’t the U.S. implement differences among bills? The cost of adapting vending machines, bank drawers, and ATMs to new bill sizes would cost billions of dollars.

6

Hard to copy

Originally, dollars were not green, but black. As time passed, green ink was favored, as it was cheap and did not fade as much as black. The new color also prevented people from using black-and-white cameras to create counterfeit money. Currently, dollar bills are predominantly green, but newer versions also include extra colors, such as pink, orange, or purple.

7

A $100,000 bill?

Have you ever seen a $500 or 1,000 dollar bill? What about a $100,000? Up until 1945, the U.S. Treasury printed $500, $1,000, $5,000, $10,000, and $100,000 notes , in addition to the values currently in use. These higher-value notes were mainly intended for bank and government use, but were sought by criminals as they made it easier to hide large amounts of money. Even though they were officially discontinued in 1969, these notes are still valid, though rare, and they have a high worth as collector's items.

8

No numbers

Unlike bills, American coins have different sizes and colors related to their value. Originally, gold, silver, and copper were used for coins, but modern coins are made of copper, zinc, or nickel. Besides their size and design, the value of each coin is printed in letters, not in numbers , alongside depictions of American presidents.

9

Liberty for all (the coins)

By law, all American coins must include six specific details : the word ‘Liberty’, the name of our country, the national motto "In God We Trust", the oldest American motto "E Pluribus Unum", the value of the coin, and the year. Each coin also includes a mint mark that shows where it was made: "P" for Philadelphia, "D" for Denver, "S" for San Francisco, and "W" for West Point.

10

A global currency

The American dollar is one of the most powerful currencies in the world, acting as a backbone for international trade and finances. It is estimated that two-thirds of the physical dollars in circulation are outside American territory. Besides the U.S. and its territories, eight sovereign nations have the U.S. dollar as their official currency, with several more accepting it as legal tender.

1

There's an unexplained billion-year gap

Look closely at the canyon walls, and you'll notice something strange: a clean, sharp line where ancient rock simply stops, and a much younger layer begins directly above it.

This geological puzzle is called the "Great Unconformity," and it represents over a billion years of rock layers that are simply absent , as though that stretch of time never happened. In some spots, rock dated 1.8 billion years old sits directly beneath rock that is only 520 million years old. Where did the missing billion years go?

The leading theory involves the violent breakup of an ancient supercontinent, but scientists are still piecing it together.

2

During the Cold War, it hid a nuclear fallout shelter

During the Cuban Missile Crisis in 1962, the U.S. government converted part of the Grand Canyon Caverns into a fallout shelter. This dry cave system, more than 200 feet underground, was stocked with enough food and water to sustain 2,000 people. Naturally, it was never occupied, and the supplies were never used.

The caverns have since been transformed into a tourist attraction, with organized tours winding through the same underground chambers that were once intended as a refuge from nuclear war. You can even book a night's stay there.

3

The Federal Aviation Administration was founded after a crash over the canyon

In 1956, two commercial passenger planes collided in midair over the eastern Grand Canyon, killing all 128 people on board both crafts. Rescue teams struggled to reach the wreckage deep inside the canyon, and the extreme heat of the crash had caused the planes' aluminum to fuse with the bedrock. There were no survivors.

The disaster exposed a terrifying truth: the U.S. air traffic control system was dangerously outdated, relying on pilots' visual estimates and rough guesswork from controllers , with no way to separate fast-moving aircraft from slow ones, or instrument-flying planes from those navigating by sight. Congress responded by passing legislation that created both the Federal Aviation Administration (FAA) and the National Transportation Safety Board.

4

A hoax suggested that an Egyptian civilization had lived there

In 1909, the Arizona Gazette reported that an explorer named G. E. Kinkaid had discovered a vast underground citadel inside the canyon, filled with artifacts linked to ancient Egyptian civilization. He even claimed the expedition had been funded by the Smithsonian.

This story described hieroglyphics on the walls, mummies in the chambers, and relics pointing to a direct connection with the Egypt of the pharaohs. It was incredibly detailed, and it was, of course, a hoax. No evidence for any of Kinkaid's claims ever surfaced.

5

Fewer than 100 people have ever hiked its full length

Among the few people who have completed the through-hike of the Grand Canyon is Jen Hogan, the first woman to accomplish it, finishing her journey in 2021–2022.

It’s a full 800-mile length below the rim. The route involves extreme heat, flash floods, near-impassable areas, and stretches with no water or trail whatsoever. Around 60 or 70 people have reportedly accomplished it. This makes it one of the most exclusive feats on Earth.

6

The Grand Canyon's rocks predate dinosaurs entirely

Visitors scanning the canyon walls for fossils are often surprised to learn they won't find any dinosaur bones here. The rock layers of the Grand Canyon are simply older than dinosaurs. This fact alone can be shocking: staring at its walls means staring at marine fossils from as far back as 1.2 billion years ago. Some of its caves hold the remains of ancient mammals. The canyon is a window into a world that existed long before the dinosaurs, when the land that is now Arizona lay beneath a shallow sea.

7

The park is bigger than Rhode Island

Numbers alone rarely capture the Grand Canyon's scale, so here's a different approach. Rhode Island covers about 1,214 square miles, and the Grand Canyon National Park spans 1,904 square miles.

The canyon's depth exceeds four Empire State Buildings (which is 1,454 feet) stacked on top of one another. That’s 6,093 feet at its deepest point.

8

But it's not the deepest canyon on Earth

For all its grandeur, the Grand Canyon does not hold the depth record. Pictured above, the Yarlung Tsangpo Grand Canyon in Tibet, China, plunges to 17,567 feet, which is nearly three times deeper. Carved by the Yarlung Tsangpo River as it cuts through the eastern Himalayas, that canyon is so remote and extreme that it remained largely uncharted until the late 20th century.

9

It is home to a pink rattlesnake found nowhere else on Earth

The Grand Canyon Pink Rattlesnake has a pinkish-red coloring that matches the canyon's own distinctive rock walls so closely that it's nearly invisible. It is found nowhere else in the world. Officially classified as Crotalus oreganus abyssus , it has darker diamond-shaped markings along its back that deepen the camouflage further.

10

There's a village at the bottom: Supai Village

For over 1,000 years, the remote village of Supai has been home to the Havasupai Tribe, the People of the Blue-Green Waters. It is located an eight-mile hike from the rim, but sits roughly 3,000 feet deep inside the Grand Canyon.

The U.S. Department of Agriculture has called it the most remote community in the contiguous United States, and it has no automobiles and no road access. The only ways in are on foot, by mule, or by helicopter. It is also the only place in the United States where the postal service still delivers mail by mule train.