What decimal system of America's did Thomas Jefferson disign?

Answer 1

Jefferson designed a decimal system for weights and measures which was proposed to Congress before the metric system (The SI system) which is now used throughout the world. He also devised a decimal system for the currency based on the Spanish dollar. The former was rejected by Congress and the US stuck to the clumsy British system, adding some further problems by redefining a gallon and so on. The US is one of a handful of countries still stuck with the Imperial system though it did adopt the decimal currency in 1792.