The wikipedia article on Metrication in the US [1] isn't the best article ever but is worth reading for mentions of previous efforts.
A few things: - the US Congress has in various ways 'blessed' the metric system, more than any other. However...
> Proponents of the metric system in the U.S. often claim that "the United States, Liberia, and Burma (or Myanmar) are the only countries that have not adopted the metric system." This statement is not correct with respect to the U.S., and probably it isn't correct with respect to Liberia and Burma, either. The U.S. adopted the metric system in 1866. What the U.S. has failed to do is to restrict or prohibit the use of traditional units in areas touching the ordinary citizen [2]
Did you know that Jefferson proposed a decimal system for the US before the SI system had come about? (See e.g. [2].) There were also proposals to measure land in decimal units rather than in 640-acre sections.
[1] http://en.wikipedia.org/wiki/Metrication_in_the_United_State...