There are currently three countries in the world that do not mandate the International System of Units — the metric system of kilometers, kilograms, liters, etc. Myanmar (Burma) is one, along with Liberia. The United States is the third. The American system of weights and measures is drawn from Britain’s, which  in turn formed theirs out of centuries of tradition. By the mid 1800s hundreds British scientists were already working on developing a more intuitive decimal system, similar to the one first adopted by France, although Britain’s politicians were slightly behind. In the U.S., however, long opposition and a quirk in the law made the metric system illegal for nearly a century.

On this day, July 28, in 1866 the U.S. fixed the loophole in the law that made the metric system illegal. As the Congressional Committee on Coinage, Weights, and Measures noted in their report, U.S. businesses that work with others countries were finding it hard to create a common measurement, as the conversion between units was necessarily imprecise.

One source of U.S. opposition to the metric system came from its more pious citizens. An International Institute for Preserving and Perfect­ing Weights and Measures met regularly met at a church in Boston to combat the “atheistic metrical system” of France. The president of an Ohio branch of the group said “We believe our work to be of God. . . . We proclaim a ceaseless antagonism to that great evil, the French Metric System. . . . May our banner be ever upheld in the cause of Truth, Freedom, and Universal Brotherhood, founded upon a just weight and a just measure, which alone are acceptable to the Lord.”