- The U.S. is finally adopting the international foot.
- Measurements are updated pretty regularly, considering they're so static otherwise.
- The change is unfathomably minuscule to anyone but big-picture measurers, like surveyors.
For a long time, America has had two feet on the ground—a problem that many experts want to solve. Consider this your periodic reminder that all measurements are slightly made up, and that even infinitesimal differences add up over a big enough scale.
The human experience is full of examples of turning an irregular real thing into a slightly imperfect form of measure. People who study and decide on measurements are called metrologists, and their activities range from deciding how to replace the solid kilogram to how tall the U.S. really is.
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It’s easy to look at a ruler or measuring cup and decide that’s the law of the land in some way, but imagine testing 20 measuring cups—do you really think they’ll all hold the exact same amount down to the drop? When you look at your ruler, do you debate whether to count the tiny width of the mark? These are all factors that make a big difference when you multiply a measurement to scale.
And it’s here we place our two feet on American soil.
Most states use an old foot that’s considered the “American foot” at this point. A few states, and the rest of the world, use an updated international foot that’s just more accurate, the New York Times reports. The analogy of the ruler marks or measuring cups still applies, because both feet were made with accuracy in mind and the difference is very small—microscopic small, down to a fraction of a fraction of an inch.
These kinds of changes are typically because the mathematics to calculate a measurement have grown more subtle or robust and we have better, more precise tools. It’s like trying a new glasses prescription and realizing something looks a little different than you thought.
The international foot dates back to 1959. At the time, Popular Mechanics covered the news:
The National Institute of Standards and Technology (NIST) has more on why we’ve had our own “survey foot” since 1959, and the agency has already updated the page with the survey foot’s imminent end in 2022. Today’s holdouts, surveyors in some U.S. states only, are exploiting a decades-old exemption. Get ready for a spicy kick:
“It was furthermore mandated that the U.S. survey foot be replaced by the international foot upon readjustment of the geodetic control networks of the United States. Although such a readjustment was completed in 1986, use of the U.S. survey foot persisted. This situation has led to confusion and errors that continue to this day, and it is at odds with the intent of uniform standards.”
The change between the old and new foots (feet?) resulted from a decision to round, the NIST explains:
“The definition adopted [in 1866 was] 1 foot = 1200/3937 meter exactly (or 1 foot = 0.304 800 6 meter approximately). In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.304 8 meter exactly.”
The extra .006 is what’s being sanded off so we can cooperate internationally.
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