Why America Still Uses the Imperial System of Measurement

In prehistoric times, not much needed to be measured. You ate what you found and lived where you could. The advent of agriculture and civilization, however, necessitated a way for people to measure their crops, take stock of their traded goods, and scale structures to increasingly glorious heights. At first, measurements were based on observable principles like the length of a person's arm. Over time, these evolved into increasingly arbitrary measurements. Once changed or modified, these measurements created a domino effect for every related unit. While most countries have adopted a standardized system, the Americans hold onto the past.

When in doubt, follow the money. Americans may believe in a certain exceptionalism but the country's adherence to the Imperial System comes down to dollars. After the Industrial Revolution solidified the country's use of the Imperial System, they held on for good. Switching everything to metric now would simply cost too much. That said, the history of measurement and the adoption of different systems traces its origins back thousands of years. Let's explore that timeline, the American Imperial insistence, and the widespread adoption of the Metric System. (For other uniquely American habits, discover American traditions that baffle the rest of the world.)

To compile an article on the history of measurement systems and why America still uses the Imperial System of Measurement, 24/7 Tempo consulted various historical, reference, and news publications. These include National Geographic, the Science Learning Hub, and CBC.com. From there, we used historical timelines and conversion systems to explore the history of measurement in the context of the American system. After that, we confirmed aspects of our research using sites like Réseau National de la Métrologie Française and Britannica.com.

Research suggests that the earliest units of measurement originated in the third and fourth millennium BC. As civilization evolved, the first measurements were likely created to calculate agricultural products, traded goods, and construction projects. These things developed rather organically as a necessary accounting for an increasing number of goods and materials. As such, the first measurement systems developed somewhat in quarantine. A particular valley or region would use a measurement system that didn't square with another area or society beyond the horizon. Furthermore, the earliest measurements existed in a vacuum. The symbols used to measure the volume of grain would have little bearing on the symbols used to measure the volume of liquids. This closed-off system extended to other goods like cloth and parcels of land.

By all accounts, cultures within the Indus Valley, Mesopotamia, and Ancient Egypt created the earliest recorded measurement systems. The Egyptian and Mesopotamian "cubit" measurements were similar. Typically, they measured the length of the forearm, from the tip of the middle finger to the crease of the elbow. For smaller measurements, the cubit was halved or quartered within the arm span. One-half cubit measured from the tip of the middle finger to the tip of the thumb. One-sixth cubit spanned the palm of the hand. To go even smaller, said cultures measured 1/24th cubit using the width of the middle finger.

Eventually, the Egyptians reworked the common cubit to the Royal Cubit by extending it to one palm. This 7-palm spread was often used in the surveying and construction of monuments, buildings, and other structures. While these became the most common form of measurement in the ancient world, ancient Indian cultures had a similar system. In their workings, they measured with units called dhanus (bow), krosa (cry or cow-call), and yojana (stage).

From there, the evolution of measurement systems becomes more murky. While historians and archeologists remain at odds over their formation, the modern-day inch, foot, and yard units likely originated from the original cubit. Whatever the case, later Roman and Greek societies adopted the foot from the Ancient Egyptians. Subsequently, the Roman foot measured out to 296 millimeters. This is further divided into 12 unciae (around 24.7 millimeters) and 16 digits (18.5 millimeters). During this time, the Romans introduced the ille passus, which worked out to 1,000 paces. Each pace equaled 5 Roman feet (around 1,480 millimeters). Furthermore, the Romans developed the earliest unit of the mile. This added up to 1,480 meters or 5,000 feet.

The Romans influenced cultures for the next thousand years, and units of measurement were no exception. During their occupation of the British Islands, they introduced the mile and it stuck. Over a millennium later, Queen Elizabeth I updated the Roman mile to reinforce her sovereignty and provide a unit better equipped for Medieval British life. As such, she changed the mile to measure 5,280 feet or 8 furlongs. A furlong equals about 201 meters.

As for the yard, it came later, but experts disagree on exactly when. Some schools of thought suggest it developed out of the double cubic while others believe it approximated the cubit itself. Regardless, the primitive yard could be divided into even parts called the half-yard, the span, the finger, and the nail. While inaccurate to the actual measurement, the yard became equated with the either circumference of a person's waist or the distance from the apex of the thumb to the tip of the nose. Some evidence suggests these measurement guides were based on the dimensions of King Henry I.

While measurements of time and mass may seem to derive from more self-evident perceptions, this was not necessarily the case. In terms of time, the Babylonians developed the first timekeeping system that squares with our modern-day estimates. They did this through the use of a sexagesimal system, also known as base 60. They treated the day like a circle, dividing it by degrees to create seconds, minutes, and hours. This extended to larger measurements of time as they divided years up on a 360-day calendar. Suffice to say, this wasn't the only way. Other cultures around the world counted time through various systems including decimal time, hour counting, and more. As evidenced above, the Romans typically divided up the day using the shadow cast by the sun on a flat stone circle with a pole called a sundial.

As for units of mass, ancient civilizations developed measurements for trade. The earliest known mass unit used a grain of wheat or barleycorn to measure precious metals like silver and gold. For larger units of mass, many cultures took their cues from the Ancient Sumerians. They used the mina, a mass unit equivalent to 1.25 pounds. On either side of the scale sat the talent (larger) and the shekel (smaller).

The exact weight of these units varied from culture to culture. While Mesopotamian societies like the Sumerians and Babylonians measured 60 shekels to one mina, the Romans unsurprisingly reworked the measurements to their liking. They calculated 1 talent as equal to 100 libra, with 1 libra being smaller in size than 1 mina. Interestingly, the carat unit used for measuring precious gems traces its origin to Ancient systems. Originally, 1 carat equaled 1 carob seed. Later, this became standardized to 1/144 ounce before evolving to 0.2 grams.

Though the English eventually adopted and modified parts of the Roman measurement system they also created their own. In the 15th century, the Kingdom of England created the troy weight system for measuring precious gems. This system is as complicated as the next, but in simple terms, 1 troy ounce equals exactly 31.1034768 grams. The English also adopted a system of mass measurement which still hints at itself in the contemporary world. This system involved units called the stone, quarter, hundredweight, and ton. At first, 1 stone equaled 16 pounds though this was later updated to equal 14 pounds. Other units were found in multiples of the stone, 2 equaling 28 pounds, 8 equaling 112 pounds, and so on. Confusingly, the English ton measurement is split into units of lesser and greater value. The long ton equals 2,240 pounds, the short ton equals 2,000 pounds, and the "tonne" equals 1,000 kilograms.

Suffice it to say, the Norman conquest of the British Isles in 1066 flipped the script again thanks to the influence of an invading culture. The development of European society during that time didn't help standardization much either. The original foot used in agriculture industries saw a reduction to 10/11 of its former size to fit the foot unit used by merchants. This caused a domino effect for other units whereby the rod, pole, or perch unit became 16 and one-half feet compared to its original 15 feet and so on. While most measurements faced the wrath of conquesting cultures and the whims of successive regents, one unit survived the tides. Once the furlong and acre became a measurement for a piece of land, they remained relatively fixed for the next thousand years.

The Imperial System traces its roots back through the centuries as well as the paragraphs in this article. The British system of measurement, once known as the Imperial System, found inspiration in the most ancient of Indus Valley cultures as well as its homegrown Saxon culture. The earliest form of the Imperial System included much of the aforementioned measurements. It seemed that with each new king, new measurements supplanted the old ones. King Edgar attempted a standardization in 965 AD when he decreed "that only one weight and one measure should pass throughout the King's dominion." Richard I reinforced this notion 200 years later. He also decreed that measurements of corn, wine, and ale should match throughout England. In a paltry but supportive move, King John extended this standardization to cloth with his signing of the Magna Carta in 1215 AD.

Unfortunately for these early kings, true standardization would elude the British grasp for centuries. All previous measurement units saw a drastic revision with the "Composition of Yards and Perches." Dated to sometime between 1266 and 1303, this statute instituted by either Henry III or Edward I reduced the length of the foot and subsequently smaller units. These hair-splitting measurement reforms continued unabated for centuries. Edward III formalized the stone to equal 14 pounds in 1340. During the Tudor Period, further reforms saw implementation. Henry VII ordered brass plaques denoting the measurements of yards, pounds, and gallons to be distributed to select towns and cities across England. His successor, Henry VIII helped further standardize measurements by banning various local units that had seeped into common use including the Tower pound (5,400 grains) and the mercantile pound (6,750 grains).

Slowly, the various British Isles coalesced under the Imperial System. The Scottish had their own measurement system. However, they abandoned it in favor of the British Imperial system under the Act of Union of 1707. Never one to fully submit to English inclinations, Ireland technically united with England under the Acts of Union 1800 but kept some variations of older measurements as per the avoirdupois system. Not ones to rest on their laurels, the United Kingdom eventually threw out all their old measurements with the Weights and Measures Act 1824. This further standardized weights and measures, particularly the gallon, as well as putting the exchequer in charge of standards custody. From there, the British would continue refining their measurements with various Acts until they adopted the Metric system in the mid-1960s.

Many people think that America sticks with Imperial to set itself apart. While there may be an element of American exceptionalism involved, the adherence to a unique system resulted from pragmatism. Like all British Colonies, the early American colonies adhered to the British Imperial measurement system. Upon revolt, however, the Americans started to see things differently. The Articles of Confederation, formalized in November 1777, put the fixing of standards of weights and measures in the hands of the central government. At the same time, it gave individual states the right to regulate said measurements.

Thomas Jefferson, however, had different ideas for the American system of measurement. During the First Congress of the United States, he affirmed the soundness of the Imperial System (IS) but worried that its providence was not under United States control. The newly developed Metric System made its way into his hands. Though he considered adopting it, he eventually resolved to keep the Imperial System. Despite his insight, little thought was given to the standards of weights and measures, and each individual state developed its own standards.

This continued throughout the 19th century until the Industrial Revolution transformed commerce and industry. The lack of measurement standardization hindered interstate trade and the government looked for a solution. This came in the form of the National Bureau of Standards in 1901 (now called the National Institute of Standards and Technology). Promptly, the Bureau called a meeting with all states. It resulted in the National Conference on Weights and Measures becoming the de facto controlling body for all American weights and measures.

Since the Industrial Revolution cemented the future of industry and commerce, by proxy, the measurements in place became set in stone. Every step on the supply chain formed around the Imperial measurement system. Machinery measured goods in IS units, workers were trained in the IS system, and just as many products were produced along this scale. At different points during the 20th century, discussions regarding the Metric System occasionally made their way to the floor of Congress. Each time, however, bills suggesting the adoption of the Metric System would be invariably stifled. Americans considered their way of doing things special and wanted to stand out from the pack of nations. Furthermore, no one, particularly titans of industry, was willing to go through the time, effort, and money required to change the entire country's measurement infrastructure. As such, they did everything in their power to frustrate efforts for change. (For American political exceptionalism, learn about the Electoral College and how it decides U.S. elections.)

Meanwhile, across the Atlantic, the French gave themselves a chance to standardize their units of measurement. While Thomas Jefferson debated one measurement system over another, the French Revolution came and went, enabling France to reform many aspects of society. One such aspect was its standard of weights and measures. In the ensuing idealism that came in the wake of the revolution, Charles-Maurice de Talleyrand-Périgord proposed a new measurement system to the French National Assembly. He aimed big, too, as this new system would be based on purely scientific principles and could be adopted globally. Since the United Kingdom showed little interest in collaboration, the French went ahead on their own. First, the French Academy of Sciences created a commission to derive the accuracy of these units. By 1799, the government approved it and rolled out the Metric System across the entire country.

Previous measurement systems like the British-derived Imperial System took cues from arbitrary scales. The Metric System, however, based its measurements on the observable features of nature. This organized itself along seven constants. The meter measured length, the kilogram measured mass, the second measured time, the kelvin measured temperature, and so on. To give the system proper grounding, the meter originally measured as one ten-millionth the distance between the North Pole and the Equator through Paris. Later, this measurement was updated to equal exactly 1/299792458 of the distance light travels in one second. The French called this grounding in natural principles the "mise en pratique." This describes at least one way in which each base unit can be measured through natural, scientific principles. When possible, these base units allowed laboratory equipment to measure without relying on an arbitrary, unscientific measurement system from another country.

Compared to the scientific elegance of the Metric System, the British Imperial System seems almost silly. It gave measurements of arbitrary scales based on the whims of kings or royal reforms. In opposition, the Metric System sought practicability, adaptability, scientific grounding, and ease of use. By rooting the Metric System in a base 10 manner, it scales easily and quickly. When in doubt, adherents to the system could use the "mise en pratique" to find scientific grounding for a given measurement. Unsurprisingly, the Metric System quickly found favor among various cultures. After its adoption in France at the turn of the 19th century, it steadily spread across Europe. Nowadays, nearly every nation on Earth has adopted the Metric System (now called the International System of Units).

The Metric System provides an unassailable scientific harmony. The only other countries on Earth that adhere to the Imperial System are Myanmar and Liberia (a former American colonization project). However, it's unlikely that the United States will ever fully adopt the International System of Units. There is too much industry, commerce, and infrastructure that relies on the Imperial System in the United States. Transferring to the Metric System would require an unheard-of transformation of society. Too much money relies on the in-place Imperial System, so no one is eager to change it.

That said, the metric system is too elegant and easy not to be implemented by meticulous American scientists. A quick glance at a ruler will show you that it contains both inches and centimeters. American school children learn the Imperial System as a priority. However, they also learn key elements of the metric system. Since the United States accepts an informal joint Metric-Imperial use, it's implausible the country will ever make the switch fully. The joint-use system can be found in Canada as well. Thanks to its historic ties with the United Kingdom, Canada incorporates elements from each system into their infrastructure. While they measure length in kilometers, weight and body length typically use the Imperial pounds and ounces. (For top place holdings, discover what the U.S. leads the world in.)