Why Doesn’t America Use the Metric System?

  • Standard meter, Paris, 1790s
Standard meter, Paris, 1790s
Credit: © Universal History Archive—Universal Images Group/Getty Images
Author Bess Lovejoy
June 25, 2026

Love it?

Credit: History Facts

As America turns 250 years old, you’ll hear plenty about the Declaration of Independence, the Founding Fathers, and the birth of a nation. But what was everyday life like for ordinary Americans? In 1776, the country looked, sounded, tasted, and felt very different from our own. Check your inbox every day until July 4 to find out what life was really like in the year the United States was born.


America’s relationship with measurement is not exactly as straight as a ruler. We buy soda in liters and milk in gallons. We run 5Ks but drive in miles. Weather forecasts use Fahrenheit, nutrition labels use grams, and rulers often list centimeters alongside inches, even if the “cm” side is frequently ignored. 

To much of the world, this is puzzling, to say the least. Nearly every other country routinely uses the metric system, a method designed to make measurements easier to calculate and universally understandable. Meanwhile, Americans continue navigating a maze of feet, ounces, teaspoons, and miles that can feel less like a coherent plan than a series of historical accidents. The idiosyncrasy of the system is hinted at in its name: U.S. Customary Units. No grand logic here, the name seems to imply — we just use it because it’s always been so.

That’s not to say the U.S. hasn’t attempted a switch to the metric system, and indeed the current measurement mix is far from metric-free. So how did we get here?

Credit: © clu—DigitalVision Vectors/Getty Images 

Where the Metric System Came From

Before the metric system, measurements were often chaotic. Different regions — and sometimes different towns — around the world used their own units for weight, volume, and distance. In France alone, an estimated hundreds of thousands of local measurement units were in use before the late 18th century.

Scientists, merchants, and government officials found this deeply frustrating. During the French Revolution, reformers saw an opportunity to create something more rational: a universal measurement system based not on tradition, kings, or local customs, but on nature itself. 

The result was the metric system. French scientists defined the meter as one ten-millionth of the distance from the equator to the North Pole along the meridian of longitude that passes through Paris. Other metric units followed from there. A liter, for example, represented the volume of a cube measuring 10 centimeters on each side.

Just as important, the entire system was decimal-based. Instead of awkward conversions — such as 12 inches in a foot, 3 feet in a yard, or 5,280 feet in a mile — the metric system moved cleanly by powers of 10. To Enlightenment-era thinkers, the system represented reason in action.

France officially adopted the metric system in 1795. Other countries followed over the next century, especially as science, engineering, and global trade increasingly demanded standardized measurements. Today, only two countries — Myanmar and Liberia — are often listed as fellow metric holdouts alongside the U.S.

How Has Life Expectancy Changed Over the Centuries?

  • Older couple on beach
Older couple on beach
Credit: © Robert Nicholas—OJO Images/Getty Images
Author Kristina Wright
April 23, 2026

Love it?

Imagine being born into a world where half the children around you never reach adulthood — and no one finds that unusual. For most of human history, that was simply life. And living into your 70s or 80s was the exception, not the norm.

Life expectancy is one of the clearest ways to understand how human life has changed — but only if we define it carefully. It does not describe the maximum age people could reach. Instead, it reflects the average number of years a newborn could expect to live based on the age-specific mortality rates of that time, a measure historians call period life expectancy.

These sometimes shocking averages help us see not just how long our ancestors could live, but also how survival itself has evolved across the centuries.

Credit: © Bettmann Archive/Getty Images 

Prehistory

Estimating life expectancy in prehistoric societies is difficult because there are no written records, so researchers rely heavily on archaeological evidence, especially skeletal remains. Most estimates place life expectancy at birth around 20 to 30 years, driven largely by extremely high infant and child mortality. Many children died before age 5, which sharply lowered the average even when adults sometimes survived into old age.

This life expectancy average does not mean adults routinely died in their 20s. Those who survived childhood often lived into their 40s or 50s, and some lived longer, as skeletal evidence confirms. Still, reaching adulthood did not ensure a long life by today’s standards. Daily life carried constant risks because, without modern medicine, minor injuries, infections, childbirth complications, food shortages, and environmental hazards could all become fatal. 

Why Did Doctors Stop Making House Calls?

  • Country doctor leaving home, 1949
Country doctor leaving home, 1949
Credit: © Bettmann Archive/Getty Images
Author Kristina Wright
March 17, 2026

Love it?

There was a time when seeing the doctor didn’t mean sitting in a crowded waiting room or logging in to a patient portal. Instead, the doctor came to you, carrying a black bag and bringing their expertise and equipment to your bedside.

Today, health care looks very different. We drive to medical campuses filled with imaging suites and labs, check in electronically, and have our patient notes transcribed by AI. The transformation has been so complete that it can be hard to imagine the house call was a central feature of American medicine little more than a century ago. So what changed?

Credit: © Debrocke/ClassicStock—Archive Photos/Getty Images 

When House Calls Were the Norm

From the earliest days of American medicine through the early 20th century, house calls were a routine part of medical care in the United States. Physicians regularly traveled to patients’ homes in cities and rural areas alike. In 1930, approximately 40% of physician visits were house calls, according to the New England Journal of Medicine.

Most doctors were general practitioners who worked with patients of all ages. They delivered babies, set fractures, drained infections, treated pneumonia and influenza, and managed chronic illnesses. Medications were often dispensed directly from the physician’s bag. Payment could be made in cash or, particularly in rural areas, in goods or services.

Doctors did maintain offices, but they were often modest — sometimes located in the physician’s home — and equipped with limited diagnostic tools. Hospitals existed, but they were typically reserved for surgery, serious trauma, or advanced illness. Much everyday medical care happened in the home.

What’s the Real Story of Isaac Newton and the Apple?

  • Isaac Newton with an apple
Isaac Newton with an apple
Credit: Hulton Archive via Getty Images
Author Tony Dunnell
June 30, 2025

Love it?

It’s one of the most iconic images in scientific history: Isaac Newton is sitting beneath an apple tree when a piece of falling fruit hits him on the head, sparking his revolutionary theory of universal gravitation. The tale has been told in countless textbooks and popular accounts, and has become a metaphor for “eureka” moments and the process of scientific discovery in general. 

But did an apple actually fall on Newton’s head? Or is this account a fanciful fiction that attached itself to the story of Newton’s brilliant scientific and mathematical insights? Here, we take a closer look at the well-known tale of Newton and the falling apple, and the truth behind one of history’s greatest scientific discoveries. 

Credit: Universal History Archive/ Universal Images Group via Getty Images 

The Story of the Falling Apple

You’re probably familiar with the basic tale of Newton and the apple tree. The story typically has a young Newton sitting beneath an apple tree in the gardens of Woolsthorpe Manor, his childhood home, which he happened to be visiting in 1666. Then, suddenly, an apple falls from the tree, hitting Newton square on the head and triggering his moment of inspiration. (Here the teller of the tale may insert a shout of “Aha!” or “Eureka!”) In this moment, Newton comes to the magnificent realization that the force that made the apple fall is the very same force that keeps the moon and planets in their orbits. And with this, his theory of universal gravitation is born. 

Why Did Doctors Wear Beak Masks During the Bubonic Plague?

  • Plague doctor, 17th century
Plague doctor, 17th century
Credit: Bildagentur-online/ Universal Images Group via Getty Images
Author Tony Dunnell
September 11, 2024

Love it?

Few images in medical history are as striking (or as creepy) as those of plague doctors with their long, beaked masks. This peculiar costume, worn by physicians during outbreaks of bubonic plague in Europe, has become an enduring symbol of the disease. But why did doctors wear these strange masks, which surely must only have added to the fear felt by people in times of suffering? What purpose did the design serve? Here’s the reasoning behind the mask, which came about in an age when the true nature of disease transmission was still shrouded in mystery.

Credit: DEA PICTURE LIBRARY/ De Agostini via Getty Images

The Origins of the Plague Doctor Costume

Contrary to common belief, the plague doctor costume was not a medieval-era invention. Despite its common association with the Black Death — the name given to the bubonic plague pandemic that devastated Europe in the mid-1300s — there is no evidence to suggest it was worn during the 14th-century epidemic or at any point in the Middle Ages. It emerged much later, in the 17th century, when plague outbreaks were still common in Europe. 

We know that the striking attire was worn in 1619 by the French physician Charles Delorme during an eruption of the bubonic plague in Paris. Delorme, who some historians credit as inventing the outfit, described the plague doctor costume in full in a mid-17th century text, complete with leather hat, gloves, a waxed linen robe, boots, and a mask with glass eyes and beak.

Plague doctors across Europe soon adopted the outfit; they also carried a stick with which to remove the clothes of the infected. The look was so widely recognized in Italy that it became commonplace in Italian commedia dell’arte — an early form of comedic theater — and carnival celebrations, and it remains a popular costume today.

7 Shocking Medical Beliefs From Ancient Greece 

  • Bloodletting a patient
Bloodletting a patient
Credit: Bettmann via Getty Images
Author Tony Dunnell
August 20, 2024

Love it?

The ancient Greeks are widely regarded as the founders of modern medicine. Yet initially, they saw illness as a divine punishment and healing as a literal gift from the gods — beliefs not uncommon in the ancient world. By the fifth century BCE, however, the Greeks began testing and advancing medical theories based on actual scientific observations — cause and effect — rather than spiritual beliefs alone. 

Three factors began to take prominence in ancient Greek medicine: diet, drugs, and surgery. Diet was particularly important and, when combined with medicine and surgery, created a holistic approach to health and healing. Still, this was more than 2,000 years ago, and the ancient Greeks never entirely separated the spiritual world from the physical. Modern medicine has come a very long way in two millennia, and today, some medical practices from ancient Greece seem strange at best, and even downright shocking. 

Credit: GraphicaArtis/ Archive Photos via Getty Images

Tasting the Humors 

The Greek physician Hippocrates was fundamental to the medical advancements of ancient Greece, and he is still revered for his ethical standards in medical practice. (Many doctors still take a modernized version of the Hippocratic oath.) Hippocrates was particularly taken by the idea that the human body contained four humors, or fluids: black bile, yellow or red bile, blood, and phlegm. In humoral theory, these fluids held the key to medical diagnosis. As such, Hippocrates routinely tasted his patients’ urine, pus, and earwax, and smelled and scrutinized their stools and vomit. You certainly can’t fault his dedication, even if such practices seem gruesome today. 

How Did Humans Survive the Ice Age? 

  • Depiction of ice age people
Depiction of ice age people
Credit: Esteban De Armas/ Alamy Stock Photo
Author Tony Dunnell
July 11, 2024

Love it?

Earth has experienced at least five significant ice ages in its history — periods in which colder global temperatures caused glaciers to expand across the planet’s surface. Homo sapiens, which emerged about 300,000 years ago in Africa, survived two such ice ages. The most recent, known as the Last Glacial Period, or simply the “last ice age,” occurred between 120,000 and 11,500 years ago. It reached peak conditions between 24,000 and 21,000 years ago, in a period known as the Last Glacial Maximum, when vast ice sheets covered North America and northern Europe. 

At that point, Homo sapiens had already spread around the world. Many of our ancestors, therefore, found themselves in a survival situation during the frigid ice age, along with animals such as brown bears, caribou, and wolves — as well as large animals known as megafauna. These impressive creatures included woolly mammoths, mastodons, and saber-toothed cats — all of which went extinct during the last ice age. 

How, then, did humans survive? It was no easy task, for sure, but our ancestors were highly adaptable. Here’s how humans not only managed to survive the last ice age, but also emerged as the most dominant species on Earth.

Credit: Wiskerke/ Alamy Stock Photo

Weatherproof Shelters

Contrary to the popular image of ice age humans — or “cavemen” — living in deep caves, our ancestors were more likely to have built sturdy rock shelters. While these shelters often made use of natural features, such as a depression in a cliff face, early humans would also have made extensive modifications to further weatherproof their shelters, such as draping large animal hides from overhangs to block out the bitter winds. With a warm fire blazing inside, these shelters provided ample protection from the cold. In the brief but slightly warmer summer months, when hunters moved out onto the open plains, they built dome-shaped huts or tents out of mammoth bones, which were then covered with animal skins. 

A Brief History of UFO Sightings

  • UFO newspaper headline
UFO newspaper headline
Geography Photos/ Universal Images Group via Getty Images
Author Tony Dunnell
March 14, 2024

Love it?

UFOs aren’t just a modern phenomenon: If we look back through history, we find that people have reported seeing unidentified flying objects since ancient times. In classical Greece and Rome, the philosopher Plutarch wrote of flaming spears and shields that moved in formation in the heavens; the historian Livy told of a “phantom navy” seen shining in the sky; and the writer Julius Obsequens told of golden spheres of fire that flew through the air. It’s only far more recently, however, that the idea of UFOs as an indication of extraterrestrial life has become established in the wider public consciousness — whether we believe in visitations from little green men or not. 

Scientifically and statistically speaking, there’s a rational argument to be made for the existence of intelligent species in the universe apart from ourselves. When it comes to UFOs, however, the question is whether these species have actually crossed the vast expanse of space to visit Earth. This is where things get complicated. As the scientist Enrico Fermi posited in his famous Fermi paradox, if there are other civilizations spread throughout the galaxy, then why haven’t we heard from them? Scientists continue to tackle the question, with theories such as the “Great Filter” (that alien civilizations have existed but were wiped out) and the “zoo hypothesis” (that extraterrestrial life exists, but is choosing not to contact Earth). Then there are the ufologists and budding Fox Mulders out there who argue that the aliens are already here — that UFOs are spacecraft from other worlds, and the truth is out there for anyone willing to accept it.

The modern history of UFOs is, of course, full of tantalizing details that have convinced many to believe that actual UFOs of the extraterrestrial variety have visited Earth and continue to do so. According to recent polling, 42% of Americans believe in UFOs, and most of these Americans believe that unidentified flying objects are alien spacecraft visiting Earth from other planets or galaxies. Here are some of the most pivotal events in the history of UFOs — events that have helped convince many people that aliens are indeed among us. 

Credit: Chronicle/ Alamy Stock Photo

Kenneth Arnold and the Flying Saucers

On June 24, 1947, a private pilot named Kenneth Arnold was flying close to Mount Rainier in Washington state when he saw nine shiny, circular objects flying in formation. Each object was about 100 feet across, and each one flew at what he estimated as about 1,200 miles per hour (roughly twice as fast as any known aircraft at the time). The report was soon picked up by the Associated Press, which described Arnold’s strange sighting of “nine bright saucer-like objects.” The story then exploded across the United States, with the new term “flying saucers” on everyone’s lips. Just like that, the modern age of UFO sightings had begun. 

Credit: Universal History Archive/ Universal Images Group via Getty Images

The Roswell Incident

Ten days before Kenneth Arnold saw his flying saucers, a rancher named W.W. “Mac” Brazel and his son were driving across their ranchland about 80 miles northwest of Roswell, New Mexico. They came across a patch of land in the desert strewn with rubber strips and metallic-looking, lightweight fabric. Baffled, they returned home. It wasn’t until weeks later on July 4 that they returned to collect the debris—unaware of the nationwide flying saucer fervor that had recently begun—which they then delivered to the local sheriff. From there, things escalated quickly, and the case passed up through the military ranks until it reached the commander of the Eighth Air Force in Fort Worth, Texas. Then, the Air Force made a curious decision. Rather than admit the true nature of the wreckage — it was a crashed Air Force balloon that was part of the secretive Project Mogul — they released an extraordinary press release stating they had recovered a “flying disk.” 

Naturally, the story spread like wildfire. The Air Force soon tried to backtrack, stating that it was actually a weather balloon carrying a radar target, but the damage had been done. To this day, conspiracy theories permeate the so-called Roswell incident, which in some accounts has been embellished to include recovered gray aliens and extraterrestrial technology. 

The Most Extreme Blizzards in History

  • Blizzard of 1888
Blizzard of 1888
Bettmann via Getty Images
Author Tony Dunnell
February 7, 2024

Love it?

When blizzards come at full force, they’re certainly nothing to sneeze at. In the most extreme cases, visibility is reduced to just a few feet, wind blows faster than traffic on the highway, and snow is so deep it’s impossible to drive — or even walk. The term “blizzard” is often used to describe any snowstorm, but the National Weather Service officially defines a blizzard as having  ““winds in excess of 35 mph and visibilities of less than 1/4 mile for an extended period of time (at least 3 hours).” That, however, is at the mildest end of the spectrum. Blizzards can become far more intense, with waist-deep snow and whiteouts bringing entire cities — and sometimes entire regions — to a standstill. Here are five facts about some of the biggest blizzards in history.

Photo credit: Bettmann via Getty Images

The Blizzard of 1888 Led to the Creation of the New York Subway

On March 11, 1888, a massive blizzard struck the Atlantic coast of the United States, from the Chesapeake Bay up to Maine. As much as 55 inches of snow was dumped in some areas, and New York City ground to a halt. Many people had to seek refuge in hotel lobbies, where temporary beds were put up. (Mark Twain was among those stuck in his New York hotel for several days.) As many as 15,000 people were stranded on the city’s elevated trains, and the drifting snow and howling winds also felled telegraph lines, water mains, and gas lines. In the aftermath, the storm was a wake-up call to city planners across the nation. There was a shift toward burying infrastructure underground, including lines of communication and utilities. The blizzard also prompted New York City to begin planning its vast subway system to replace the exposed high-line trains.  

The History of Calendars, in 7 Facts

  • The Gregorian calendar
The Gregorian calendar
PHAS/ Universal Images Group via Getty Images
Author Anne T. Donahue
December 21, 2023

Love it?

The humble calendar of one of civilization’s oldest staples. The earliest means of measuring days and weeks dates back 10,000 years, and timekeeping techniques adopted by the ancient Babylonians, Egyptians, and Romans slowly evolved into the calendar we use today. Yet the emphasis here is on “slowly.” The evolution from charting moon phases to separating seasons to measuring fiscal years was one of controversy and chaos across centuries. Still, humans never stopped working to perfect how we mark the passage of time. Here’s a brief look at the fascinating history of calendars, just in time to start a new one.

Photo credit: Buyenlarge/ Archive Photos via Getty Images

The First Known Calendar Is From Prehistoric Scotland

In 2013, British archaeologists discovered what they consider the world’s oldest calendar, dating back to around 8000 BCE. The prehistoric calendar, located at Warren Field in Scotland, consists of 12 pits believed to have contained wooden posts representing months of the year. Positioned to chart lunar phrases, the pits are aligned with the southeast horizon and were likely used by hunter-gatherer societies to track seasons. The site precedes Stonehenge by several thousand years.