Figure 1. Countries using the metric, imperial, and US customary systems as of 2019
Image Credit: Goran tek-en via Wikimedia Commons, CC BY-SA 4.0
The United States continues to primarily use the United States Customary System of Measurement. This was derived from British Imperial System, though some of its units, especially for volume, differ somewhat. The British Imperial System was developed and officially used in Great Britain from 1826 until the British Empire transitioned to the Metric System in 1965. Both the United States Customary Stem of Unit and the British Imperial System use units like inches, feet, miles, acres, pounds, tons, gallons, ounces, and Fahrenheit. Some of my friends jokingly call them "Freedom Units" to emphasize our unique American tradition of doing things our own way. It’s somewhat ironic that, after fighting for independence from Britain, we continue to hold on to the measurement units that came from there.
The International System of Units, known by the international abbreviation SI in all languages, is the modern form of the metric system and the world's most widely used system of measurement. The United States is one of only five countries in the world that has not fully adopted this system.
Perhaps it is even more ironic that the efforts of George Washington, Thomas Jefferson, and Benjamin Franklin are largely responsible for the final development of the metric system in France in the 1780s and its adoption there in the 1790s. It started in 1782 when Thomas Jefferson argued for a decimal currency system with 100 cents in a dollar. The idea was that all money could be subdivided by decimal fractions to make our currency easier to use and more desirable on the world stage. George Washington called for uniformity in the currency, weights, and measures of the United States of America in his second and third State of the Union Addresses. Benjamin Franklin and Thomas Jefferson served as ambassadors to France, where they were both active in the scientific community. Both men were active in promoting the ideas of decimal currency and decimal measurements to the French Royal court and to highly influential scientific philosophers, who finalized the development of the metric system.
Figure 2. Thomas Jefferson, Benjamin Franklin, and George Washington
Image Credit: Wikimedia Commons, Thomas Jefferson, Benjamin Franklin, George Washington, Public Domain
Throughout the 19th century, as the rest of the world began to accept the metric system, it was many times proposed that the U.S. transition toward the International System. However, since the United States was one of the earliest leaders of the industrial revolution and had already created a lot of equipment based upon U.S. customary units, American industrialists regularly lobbied Congress to delay adopting the metric system.
In the 1970s, a new movement to adopt the metric system emerged in the U.S. In 1975, Congress passed the Metric Conversion Act designed to “coordinate and plan the increasing use of the metric system in the United States”, and established the Metric Board to guide America’s transition. The transition was legally voluntary. Speedometers in automobiles and highway speed limit signs began to show both MPH and KPH (and some used only KPH). Soft drink manufacturers determined that since their products had a long shelf life and were shipped all over the world, adopting the International System of Units for many of their bottles was to their competitive benefit. On the other hand, milk, a far more perishable product typically sourced from a nearby producer, never made the transition. To this day, milk is still sold in the U.S. in pints, quarts, and gallons. In 1982, public opinion turned against the transition, the Metric Board was dismantled, and the push towards the metric system waned again. Support for moving to the Metric System is the right thing to do, but it appears to be politically perilous in the U.S.
We Already Use the International System of Units, in Some Cases
Our currency is largely based on the metric system. Some running races use the metric system. If you are a long-distance runner, you’ve likely run several 5k or 10k races. Many drinks are sold in volumes measured with the metric system. 1, 1.5, and 2-liter bottles have been common in the U.S. for decades, and I happen to have more than one 750ml bottle in my house right now. The Metric System is already the primary system of measurement in the science and medical fields, and the U.S. Military has used metric measurements for decades to ensure compatibility with allies.
Why the U.S. Should Complete our Conversion to the International System of Units
The Metric System is more logical because it is based on tens. There are 10 millimeters in a centimeter, 100 centimeters in a meter, and 1000 meters in a kilometer. In comparison, the U.S. Customary System has 12 inches in a foot, 3 feet in a yard, and 1,760 yards in a mile. Most people in countries that use the U.S. Customary System don’t know that there are 1,760 yards in a mile.
Science is conducted using SI units. If we want to have a scientifically literate populace and a competitive workforce, it would help immensely if our scientists and non-scientists used the same system of units.
The United States is the only industrialized nation that has not adopted the International System of Units, and it puts the United States at a trade disadvantage. Our scientists need to learn two systems of measurement. Many U.S. manufacturers have the added expense of making two kinds of products for every item, one for domestic sale and one for export.
Our need to convert between two different measuring systems often results in mistakes. A famous example of this was the destruction of the Mars Climate Orbiter in 1999. The navigation team at the Jet Propulsion Laboratory (JPL) used the International System of Units (in this case, meters and kilograms) in its calculations, while Lockheed Martin Astronautics in Denver, Colorado, which designed and built the spacecraft, provided crucial acceleration data in the U.S. Customary System of inches, feet, and pounds. As a result, it descended too low in the atmosphere and burned up. The total cost of the project was estimated to be $327.6 million between the research, development, manufacturing, and launch expenditures.
Figure 3. Mars Climate Orbiter
Image Credit: Wikimedia Commons, Public Domain
The ECRI Institute (originally known as the Emergency Care Research Institute), listed medical errors due to Metric/Customary conversion mistakes as the No. 7 concern of their Top 10 Patient Safety Concerns.
Switching would briefly be hard, but from then on using the International System of Units would be easier for all of us. Teaching our children about units and subunits by moving the decimal right and left would be a lot easier than our current system.
George Washington, Benjamin Franklin, and Thomas Jefferson were right on this issue. The United States should finish adopting the metric system (International System of Units). It’s the international standard for science, medicine, and commerce. It's also more logical. That’s my position, and I will not budge one centimeter.
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