Meters and litres. It’s an unusual plank for a presidential platform, but Lincoln Chafee, the former US senator from Rhode Island — who was first a Republican, then an independent, and now a Democrat — said in his campaign announcement this week that the U.S. ought to convert to the metric system.

It highlights our lengthy history with the measurement system used by everyone else, besides fellow holdouts Liberia and Myanmar.

But the U.S. wasn’t always so lonely. The U.S. started down the highway to metrication, but pulled over the side of the road. Don Hillger, the president of the U.S. Metric Association, says the golden period for metric fans was around 1980. “Many former British Commonwealth, English-speaking countries in the world decided that they were going to adopt the metric system,” he says.

Canada went metric in the 1970s. They had a plan and a public awareness campaign. One of their ads, which featured a cartoon shoveling his stoop, says “100 centimeters of snow … is an awful lot of snow.”

That’s what works, apparently, a cultural change that helps people imagine the differences between old and new. Hillger says the problem here is the Metric Conversion Act of 1975 had one deadly word: voluntary. “I think they thought that, well, it would probably happen because big, larger companies change and then the other ones follow.”

As you know, that didn’t quite happen.

But Elizabeth Gentry, the metric coordinator at the National Institutes of Standards and Technology says a lot of big companies did convert after that act: Caterpillar, GM, IBM. Plus, an entire industry: booze.

“They modified the law to permit the use of metric units on the packaging,” Gentry says.

She says that business-focused change helped Americans become comfortable with liters and grams… that’s why you know what a two-liter bottle of coke looks like:

Daniel Case/Wikipedia/Creative Commons

In fact, metric is officially America’s preferred system for trade and commerce. Meters in the office, inches at home. This exact problem was identified in our own metric cartoon from the 1970s: