The United States is one of only three nations on the earth that does not use the metric system for standard weights and measures. The outdated and archaic imperial/US customary measurement system has long outlived its usefulness. SI/metric is the common language of most of the world's science and technology, not to mention the daily discourse of nearly all other people on the planet.
Metrication of the US has been slowly underway since 1971, and still appears to be considered voluntary by the Department of Commerce some 43 years later. The last steps are most likely going to need government influence to require the final, complete jump to the new system.