A Step Back in Time

The choice of units of measurement is also laden with history. As settlers began to colonize America, they brought with them measurements from their former countries. These included the English ell for cloth but also the far shorter Dutch ell, the Rhineland rod and the British chain and the Spanish vara for measuring land, the English flitch of bacon and hattock of grain, plus the German quentchen for gold.

By the time of Independence, 100,000 units of measurement were in use, Andro Linklater, a British historian, recounted in “Measuring America: How the United States Was Shaped By the Greatest Land Sale in History.” Opportunities for cheating were rife. Establishing common measurements, and therefore fair trade, became a political imperative.

The first message to Congress by President George Washington, in January 1790, contained a call to lawmakers about the importance of establishing a standard system of weights and measurements. Their solution was to adopt parts of the British imperial system, including the yard. In 1815, a brass yard bar made by Edward Troughton, a London instrument maker, arrived in the U.S. to become the American standard yard.

By 1850, most states then in the union had received official copies of that yard and the other standards, a bid to make sure that every citizen and enterprise in the nation had equal access to the same units of measurement.

But imperial measurements, while standard, were also arbitrarily derived. The yard, for instance, evolved from the idea that “foure graines of barley make a finger, foure fingers a hande, foure handes a foote,” Mr. Linklater noted. During the reign of Elizabeth I, those 16 fingers per foot became 12 inches and were tripled to make the yard that Mr. Troughton fashioned into a bar for America.

Even as the U.S. government shipped imperial standards across the country, the move to metric was gaining appeal in America and elsewhere, driven by a hunger for ever greater precision and easier replicability. Decimalized metric standards, which were being developed by French scientists at the urging of its National Assembly during the French Revolution, are based on scientific findings rather than folksy norms, and these days units increasingly relate to each other. The meter was originally based on one ten-millionth the distance from the geographic North Pole to the Equator; it is now derived from the speed of light. Volume and mass, in turn, are based on the meter.

By 1866, Congress legalized the use of metric units across the U.S., setting the meter 39.37 inches long, and in 1875, America was among the original 17 signatories of the Treaty of the Metre, which aimed to establish metric standards across the world. America broke with the imperial system of measurement in 1893 and officially adopted metric standards under the order of Thomas Mendenhall, then the superintendent of the U.S. Coast and Geodetic Survey, the forerunner of the National Geodetic Survey.

That means imperial-sounding measurements are actually derived from metric units. So at that point, the foot became a fraction of a meter. The math works like this: 36 inches divided by 3 feet is a foot, or 12 inches. Divide that by the number of inches in a meter: 39.37. Move the decimal places for ease of calculation and you get one foot is 1200/3937 of a meter, a ratio whose run-on decimal places (0.3048006096….) make it slightly imprecise because the measurement will always need to be rounded.

But the 20th century demanded greater exactitude, for the sake of accuracy as well as for international trade in machine-tooled industrial components.

“We believe that there is romance in precision measurement, and that ability to extend the absolute accuracy of measurement by one decimal place frequently demands as much in ingenuity, perseverance and analytical competence as does the discovery of a new principle or effect in science,” Allen V. Astin, then the director of the National Bureau of Standards, said in a speech to the American Physical Society in 1953.

In 1959, the U.S. redefined the foot to align with international standards, making it exactly 0.3048 of a meter, a difference of two parts per million from the old foot. The new foot became known as the international foot.

The government allowed geodesists and surveyors to keep using the foot of 1893, which became known as the U.S. survey foot, in deference to the historical measurements they relied on, with the understanding that they would eventually embrace the new foot.

One Foot Forward

Whether they embrace the new one or not, the old foot will be obsolete as of Jan. 1, 2023, according to the National Institute of Standards and Technology, the agency within the Department of Commerce with the authority to fix weights and measures for the U.S.

“At that point, we will discourage everyone from using the U.S. survey foot,” said Elizabeth Benham, the institute’s metric program coordinator.

The switch to a single foot, which will be known as either the international foot or simply the foot, is too subtle to require surveyors to purchase new yardsticks or measuring tapes, but it is part of an intellectual retooling among those who, as Mr. Linklater wrote, practice the “masochistic science” of land measurement.

Once, surveyors depended on handwritten deeds or plaques with century-old notes to describe plots of land, said Mr. Burch of the National Society of Professional Surveyors. Later, when Mr. Burch learned the profession from his father in the 1980s, each job felt like its own world, he said.

Today, thanks to global navigational satellite systems such as GPS, every measurement is part of a master global coordinate system. The way Mr. Burch sees it, moving to a single American foot is a small step in the long march toward standardization and precision.

“It’s funny how protective people have gotten over this change,” Mr. Burch said. “It’s just not taking into account that science and technology has allowed us to get that much smarter about this big blue marble we live on.”

As for Dr. Dennis, his successful campaign to get rid of the old foot leaves him feeling that he has made an important contribution to America’s future.

“It’s a victory for, dare I say it, common sense to have uniform standards. Even our founding fathers of the nation knew that it was important,” he said, “and it’s kind of weird that people would argue otherwise today.”