* 1 Spanish Milled Dollar = 1 US Dollar
1792
* 1 US Dollar = 1,600 Grains of fine silver (Coinage Act of 1792)
1834
* 1 US Dollar = 412.5 Grains of fine gold or 23.22 Grains of fine silver (Gold Standard Act of 1834)
1879
* 1 US Dollar = 23.22 Grains of fine gold (Specie Payment Resumption Act of 1875)
1934
* 1 US Dollar = 13.714 Grains of fine gold (Gold Reserve Act of 1934)
1971
* 1 US Dollar = No gold backing (Bretton Woods Agreement ends)
1973
* 1 US Dollar = 0 Grams of fine gold or fine silver.