Dollars Pictures

History
The first dollar coins issued by the United States Mint (founded 1792) were similar in size and composition to the Spanish dollar. The Spanish, U.S. silver dollars, and Mexican silver pesos circulated side by side in the United States, and the Spanish dollar and Mexican peso remained legal tender until 1857. The coinage of various English colonies also circulated. The lion dollar was popular in the Dutch New Netherland Colony (New York), but the lion dollar also circulated throughout the English colonies during the 17th century and early 18th century. Examples circulating in the colonies were usually worn so that the design was not fully distinguishable, thus they were sometimes referred to as "dog dollars".
The U.S. dollar was created and defined by the Coinage Act of 1792. It specified a "dollar" to be based in the Mexican peso at 1 dollar per peso and between 371 and 416 grains (27.0 g) of silver (depending on purity) and an 'eagle" to be between 247 and 270 grains (17 g) of gold (again depending on purity). The choice of the value 371 grains arose from Alexander Hamilton's decision to base the new American unit on the average weight of a selection of worn Spanish dollars (and later Mexican peso). Hamilton got the treasury to weigh a sample of Spanish dollars and the average weight came out to be 371 grains. A new Spanish dollar was usually about 377 grains in weight, and so the new U.S. dollar was at a slight discount in relation to the Spanish dollar. The gold equivalent of the Spanish dollar in sterling was ₤1 = $4.80, whereas the gold equivalent of the U.S. dollar was ₤1 = 4.86⅔. This exchange rate with sterling remained right up until Britain abandoned the gold standard in 1931.