While most nations use the metric system—those units of decimals that are universally employed in science—the U.S. still clings to pounds, inches, and feet. Despite several high-profile attempts to change that, Americans refuse to convert.

Thomas Jefferson first tried to move the nation toward a decimal-based system in 1789. But without support from scientists, his idea flopped. More than a century later, in 1906, telephone inventor Alexander Graham Bell told Congress that "few people have any adequate conception of the amount of unnecessary labor involved in the use of our present weights and measures."

Strong words, but still no change.

Things looked promising in 1968, when Congress authorized a three-year study that eventually recommended converting to metric and laid out a 10-year plan to get there.