According to the United States National Institute of Standards and Technology (NIST), America almost adopted the metric system, were it not for some meddling British pirates in the Caribbean.
In 1793, Thomas Jefferson sought to introduce the metric system in the United States (this process is called "metrication"). Jefferson requested measurement standards to be brought from France to implement metrication in the American states.
The French and the Americans were best buddies at the time, while the British were still bitter over their loss in the American Revolutionary War - losing those 13 American colonies marked the end of what we now refer to as The First British Empire.
Enter Joseph Dombey, a French botanist and physician, and the major participant in what we now call The Dombey Affair.
Here's a bust of Dombey:
To answer Thomas Jefferson's requests for measurement standards, the French sent Dombey, a respected scientist and explorer, to America. Dombey carried with him two standards made of copper: a standard measure of length (a meter), and a standard measure of mass (a kilogram, then called a "grave"). Dombey was to meet Jefferson in Philadelphia, and the meter and kilogram were to be introduced to the States as their measurement standards.
Here's a centuries-old grave now owned by the NIST museum:
Dombey's ship never made it to America. While in the Caribbean en route to America in 1794, it was boarded by pirates. The pirates were British privateers; they had tacit approval from the British government to plunder maritime vessels and keep a portion of the profit for themselves. Today we would call this state-sponsored terrorism, but in the 18th century, privateering was a common tactic in maritime life, openly utilized by various countries.
When Dombey's ship was boarded by the pirates, he tried to disguise himself by quickly putting on the clothes of an ordinarily sailor, but he was outed by his unusual accent. The pirates imprisoned him on the Caribbean island of Montserrat, where he died. The ship's cargo, including the copper standards, was auctioned off. The standards eventually found their way into American hands, but by then, it was too late.
I found this beauty on the NIST website. Looks like a creative NIST graphic designer has added a grave standard to a pirate flag, creating a fine flag for a metric rebel.
English/metric measurement error in the Mars Climate Orbiter