The US is moving toward the metric system, slowly. Federal efforts may have largely stalled during the Reagan admin (though things like requiring metric labelin

The US is moving toward the metric system, slowly. Federal efforts may have largely stalled during the Reagan admin (though things like requiring metric labeling on products still eventually made it through), but there's nothing stopping individual states from requiring metric in more places, e.g. road signs. As for why no state has bothered to do so yet, it's likely because there's currently a thousand more pressing issues to expend political capital on first, many of which are existential crises in a way that metrication is not.