In the late 1700s, Thomas Jefferson wanted the United States to adopt a unified system of measurement and saw the metric system as the best solution. However, a pirate attack in the Caribbean disrupted these plans. Joseph Dombey, a French scientist carrying a kilogram and meter stick to demonstrate the metric system, was captured by pirates. By the time France sent another scientist to explain the system to the Americans, Jefferson was no longer in office, and plans to go metric were disregarded.
And it sounds like Jefferson was already familiar with it anyway, if he was thinking it was the best system. I find it very doubtful that the only holdup was that there was no one to demonstrate it.