Why doesn’t the United States use the metric system yet?

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For more than 200 years, Americans have avoided using the metric system.

We thought the metric system was just something pitched to — and largely ignored by — recent generations of schoolchildren. Wrong! It’s actually been pitched to and ignored by schoolchildren and adults for about two hundred years.

There was even a law put in place in 1866 — just a year after President Lincoln was killed — to try to get Americans to go metric.

Then, by an act of Congress in 1866 (HR 596) — signed by President Andrew Johnson — it became “lawful throughout the United States of America to employ the weights and measures of the metric system in all contracts, dealings or court proceedings.”

Did that law change everything? As seen in the article below from 1900, that’s a big no.

That story explained a bit of the history of the metric system, and introduces the 1902 legislation that would require the federal government to use the newer measurements exclusively. In the end, though, the law was defeated by a single vote.

That’s part of why, more than 120 years later, we’re still happily using our feet and inches, gallons and pints, miles and degrees Farenheit.

The modernized metric system (1968)

Here’s a visual guide and introduction to the metric system that was created by the US Department of Commerce in 1968. 

That means that these colorful infographics came out even before we landed on the moon.

It was literally simpler for our country to send people into space on a rocket (and bring them back) than it was to convince the American people to use centimeters and kilograms.

The modernized metric system - From the US Dept of Commerce 1968 (4)

The modernized metric system - From the US Dept of Commerce 1968 (1)

The modernized metric system - From the US Dept of Commerce 1968 (2)

The modernized metric system - From the US Dept of Commerce 1968 (3)

Too stubborn to switch to metric?

In 1995, the US Department of Transportation explained why they thought we were still behind the metric curve.

“Americans are stubborn. One of the biggest obstacles to adopting the metric system in the United States has probably been our inherent dislike for anything that divorces us from the ‘feel’ or ‘sense’ of our traditional values for weight, measurement, distance, and speed. An example is the resistance to the transition to metric highway signs.”

But that’s not to say that nothing has changed. In fact, while we may stubbornly hang on to our old-fashioned measurements, every year we end up using more and more metric measurements. It just sort of slips into life — like when grocery stores started to sell 2-liter soda bottles. 

Metric system promo chart and base units (1972)
1970s chart of the modernized metric system from the “Brief History of Measurement Systems” by the United States National Bureau of Standards (1972)

Elizabeth Benham at the National Institute of Standards and Technology (NIST) wrote in 2020 that, while it’s true that metric use is mandatory in some countries and voluntary in others, all countries have recognized and adopted the metric system (International System of Units or SI), to some degree — including the United States.

She goes on to provide some interesting metric facts:

  • We use the SI every second of every day. After all, the second (s) is the SI base unit of time.
  • US coins & currency are produced using metric specifications.
  • Many US products, like wine and distilled spirits, have been successfully sold with only metric measures since the early 1980s.
  • Metric units are used extensively on packages to provide net quantity, nutrition, and health-related information, and for prescription drugs, over-the-counter medicine, vitamin supplement dosing, and other consumer products.

And although “US customary units” are still seen alongside metric units on product labels and merchandise literature, Benham says that it’s common for the goods themselves to be made using SI-based manufacturing processes.

Why? She says that while some businesses are concerned that consumers expect to see customary units on the package, when it comes to manufacturing processes, they are under constant pressure to stay competitive.

Adopting the latest science and technology, says Benham — much of which was developed using metric design practices — enables innovation. And that, indeed, is looking to the future.

American Joins a Metric World (1976)

A wealth of educational information was produced by the US government in the 1960s and 1970s, including this hopefully-titled brochure “American Joins a Metric World,” published in 1976.

The metric system, 70s-style

“It is therefore declared that the policy of the United States shall be to coordinate and plan the increasing use of the metric system in the United States and to establish a United States Metric Board. . .” (Metric Conversion Act of 1975)

On December 23, 1975, President Ford signed into law the Metric Conversion Act, establishing for the first time a national policy in support of metric measurement and ending a dilemma that had continued throughout the entire history of the Republic.

George Washington had raised the issue of a more uniform system of weights and measures in his first mes-sage to Congress on January 8, 1790. John Adams and Thomas Jefferson became strong advocates of that idea, speaking favorably of the recently-developed French metric system.

Instead, the young Nation followed the tradition inherited from the British, the “customary” system of measurement.

In 1875, the United States committed itself to metric by signing an international agreement, the Treaty of the Meter. This treaty was followed more in the breach than the observance.

Inches, not meters, continued to reign supreme at home, although one result was that, ever since 1893, our national measurement standards have been metric. Now at last, with the signing of the new law, the dilemma has been resolved through a national policy of coordinating the increasing use of metric in this country on a voluntary basis.

American Joins a Metric World - Info from the 1970s

The impetus for such a policy has come from our business community, which has been gradually adopting metric over the last decade. Our schools have also begun to emphasize metric, and it is apparent that the country would have drifted through metrication in an uncoordinated way unless action had been taken at the national level.

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The Metric Conversion Act of 1975 created a U.S. Metric Board, appointed by the President with the advice and consent of the Senate.

The Board consists of 17 members representing the various economic sectors affected by the metric changeover. These include engineering, science, large and small business, organized labor, education, manufacturing, consumers, weights and measures officials, State and local governments, and the construction industry.

The Board’s function is to devise and carry out a broad program of planning, coordination and public education consistent with other national policies and interests. This legislative action is, in part, the result of the comprehensive, 3-year study performed by the National Bureau of Standards for the Secretary of Commerce and submitted to the Congress in July 1971.

Metric comparisons - conversion guide from 1976 (2)

This study recommended that the United States change to the metric system deliberately and carefully through a coordinated program.

The purpose of the Metric Conversion Act of 1975 is to accomplish this goal. It allows the development of a rational plan for a voluntary change-over. In this way, metric will come as the various sectors of our economy are ready for it — and not before.

MORE: Old-fashioned cooking measurements & equivalents

In fact, metric has come to many sectors of American life over the past several years at an ever-accelerating but erratic pace. Industry continues to take the lead in the private sector.

Metric comparisons - conversion guide from 1976 (1)

At least 37 major corporations have announced policies to convert their operations. The total sales of these companies exceed $130 billion, and the list contains four of the Nation’s 10 largest firms.

Some of the first metric-minded corporations included: Caterpillar Tractor, Chrysler, Ford Motor Company, General Motors, IBM, International Harvester, Minnesota Mining and Manufacturing [3M], Travelers Insurance, and Xerox.

Whereas until just recently the metric changeover was found predominately among manufacturers with overseas interests, some of America’s largest retailers have gotten on the bandwagon. Sears, Roebuck and Company, Montgomery Ward and Company, and JC Penney are notable leaders in this category.

When they introduced the metric system of weights & measures in 1900

The North Platte Semi-Weekly Tribune (North Platte, Neb.) December 21, 1900

The bill introduced by Congressman Shafroth providing that on and after January 1, 1903, the weights and measures in the metric system shall be the legal standard weights and measures in the United States is simply another in a long line of attempts to supplant the present awkward system by the easy and simple metric, or decimal, system.

Though the bill has been reported favorably by the committee on weights and measures, it has still been a hard fight before it. The chances for its adoption are not the brightest.

In one sense, the United States may be said to have been even before France in the adoption of at least a portion of the metric system. In 1785, congress adopted the decimal system of money, with the dollar as the unit, whereas the metric system proper was not adopted by France until 1795.

The metric system’s basis

The basis of the metric system, the meter, was determined by two French astronomers and mathematicians and is exactly one-forty-millionth part of the circumference of the earth on the meridian of Paris.

The meter is 3.37 inches longer than the American yard. It is the standard of the measures of length and all other measures are based upon it. Thus the metric unit of surface measure is the centare, which is one square meter. The unit of capacity is one liter, which is the cube of one-tenth of a meter. The unit of weight is the gram which is the weight of a cubic centimeter of water.

A standard meter was constructed in 1799 by an international commission representing France, Holland, Sweden, Switzerland, Denmark, Spain, Savoy, and the Roman, Cisalpine and Ligurian republics. It was made of platinum and was deposited in the palace of archives in Paris and was declared to be the definitive basis of the metric system forever.

Law in France in 1801

The use of the metric system was declared obligatory in France on November 2, 1801, but the French people were not prepared for so sudden a change, and in 1812, a compromise was adopted which lasted until 1837. In that year a law was passed making the use of the metric system obligatory and ordering its enforcement after January 1840.

At present, it is universally used by France, as well as by all European nations, except Great Britain — where it is allowed, but not compulsory. Russia was the last of the great powers to make the change, having put the metric system into force only a few weeks ago.

On the continent, the metric system has been adopted by Mexico, Brazil, Chile, Peru, and other of the South and Central American republics.

Folding rulers
Photo by kinek00 via Twenty20

Metric system attempts over the years

As early as 1817, the subject of adopting the metric system in the United States was agitated. John Quincy Adams was appointed to investigate the weights and measures of the United States and he found that the standards of weight, measure, and capacity differed considerably in the different states and even in the same state.

He reported fully on the result of his investigation and did not favor the adoption of the French or metric system because of the popular repugnance to a change and the inconvenience which would follow the adoption of a new system. At the same time, he declared his belief that the metric system was almost ideal and reflected the greatest credit on the men and on the age which had devised it.

In 1830, another investigation was made and it again was found that a pound or a yard in one state or city was often more or less than in another. As a result, the treasury department was authorized and instructed to have made copies of the standards of weight and measure then in its possession, a set of which copies were to be delivered to the governor of each state in the union.

In 1866, it was made by an act of Congress lawful to employ the weights and measures of the metric system throughout the United States, and the secretary of the treasury was instructed to furnish the governor of each state a set of standard weights and measures of the metric system for the use of the respective states.

Under the regulations of the international postal convention, the metric system was adopted as the standard in all transactions between the nations which are members of the postal union, and accordingly, the mail matter transported between the United States and fifty other countries — including even the mail sent between the United States and England — is weighed and paid for entirely in terms of the metric system.

In 1875, a convention was held by representatives of practically all the civilized nations, except England, at which a “scientific and permanent bureau of weights and measures” was established at Paris, the expenses of which are paid by all the powers party to the convention. Great Britain has since become a party to this conference and now pays its share of the expenses of the bureau.

Americans avoiding using the metric system

One duty of the international bureau of weights and measures is to furnish exact and correct copies or duplicates of the standards of weight and measure to the several countries which contribute to its support.

These new standards were supplied to the United States and were received by the president and his cabinet on January 2, 1890, and are now deposited in a fireproof room in the coast survey building at Washington.

In 1893, the secretary of the treasury ordered that thereafter the standard meter and kilogram, deposited in the coast survey building, should be recognized as the fundamental standards from which the customary units of the yard and the pound should be derived. It is, therefore, true that at present the United States is using a system of weights and measures which is based on the units of the metric system.

The metric system proper is now exclusively used by the United States marine hospital service, by the foreign department of the post office, by the United States coast and geodetic survey, to some extent in the mint, United States signal service, and United States census department.

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