It is actually National Metric Week in the USA, (because it includes the tenth day of the tenth month, of course). It has been celebrated since 1976 after the US government passed the Metric Conversion Act, which "designated the metric system as the preferred system of weights and measures for US trade and commerce, and directed federal agencies to convert to the metric system, to the extent feasible, including the use of metric in construction of federal facilities." In fact, the USA has been promising to go metric since it was an original signatory to the 1875 Treaty of the Meter. The U.S. Metric Association has been promoting the idea since 1916.
The law of the land reads that “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." So what happened? Why, in this glorious week of 10/10 in the hundredth year of the U.S. Metric Association, are Americans still using feet, pounds, gallons and degrees Fahrenheit? When it is clearly as silly and outmoded as this year's Super Bowl LI?
According to Science ABC,
The 13 former British colonies in the USA had already gained independence from the British by the time the metric system was created. Being geographically distant from other countries, US citizens hardly had any incentive to change the way they functioned based on the metric system. Therefore, they continued to use their traditional units.
OK, but now we have airplanes and telephones and internet. And the law. Why are Americans not using metric? Blame Ronald Reagan, actually. According to John Bemelmans Marciano, writing on a website appropriately named What it means to be an American,
Americans were perhaps never more anxious than in the 1970s, and the Metric Conversion Act of 1975 is partial proof of that. American society turned unusually introspective in those post-Watergate days, even leading us to elect Jimmy Carter, the president who told Americans about their shortcomings like no other. Ronald Reagan’s election sprang from a more familiar American attitude—that our problems were caused not by questioning our core values, but by drifting away from them. And it was Reagan’s axing of the U.S. Metric Board during his 1982 budget cuts that was seen as the deathblow to American metrication.
Marciano is quoted in another article in the Atlantic:
President Ronald Reagan, using public opposition to his advantage, dismantled the U.S. Metric Board in 1982. It was a move that John Bemelmans Marciano called “the day the metric died” in his book Whatever Happened to the Metric System? Unlikely characters such as the novelist Tom Wolfe weighed in, defending customary measures as both more civilized because they’re based on human scale (i.e. a foot is supposed to be about the size of a real foot in a shoe, an inch about the width of your thumb) and more American because, of course, America was the only country using them. Marciano chalks up metric’s 1980s defeat primarily to the typical public resistance to change combined with the nation’s love affair with Reagan’s budget cuts.
The labor movement wasn't into metrification either:
Love it or hate it, there is no question that a uniform global system of measurement helps cross-border trade and investment. For this reason, labor unions were among the strongest opponents of 1970s-era metrication, fearing that the switch would make it easier to ship jobs off-shore. (Which it did.)
But times have changed, most of American industry has gone metric, and these days it might actually increase American competitiveness in the world. The NIST blog Taking Measure notes that our cars may have MPH on the speedometer but "the truth is that the car was designed and built using metric measurements. This is a good metaphor for the state of metric in the America: Under the hood we’re metric; it’s the part that people see that isn’t."
They have a plan:
Opportunities exist for people like you and me who want to see more metric use in everyday life. Let’s ask for more metric units in media. Let’s simplify product packaging labels to list only metric quantities. Let’s prevent medical dosage errors by using only milliliters, not tablespoons or teaspoons. Let’s help children build familiarity in metric by providing daily opportunities to practice using metric measures as much as they can, at both home and school.
If nothing else, from the crashes of the Mars Climate Explorer to the near-disaster of the Gimli Glider, we know that conversion errors are dangerous and expensive. (I got the biggest speeding ticket of my life getting this screwed up between the two systems and was caught driving 60MPH in a 60 km/hr zone)
After a hundred years, perhaps it's time for a change. What do you think?