Though the United States dollar was officially adopted in 1785, paper currency didn't fully enter circulation until the Civil War. The current appearance of modern US bills developed only after a long period of economic development based on commodities and coinage. The earliest form of currency used on the North American continent includes Native American beads and coins minted in Europe. Given the choice, which form of currency would you want to revisit? Does the barter-based wampum appeal to your sensibilities, or perhaps a gold and silver system that would literally weigh you down?