The Coinage Act of 1792 created the United States Mint, but the first U.S. dollars were not as popular as the Spanish dollars, which were heavier and were made of finer silver. The Spanish dollar was the first coin upon which the original United States dollar was based, and it remained legal tender in the United States until the Coinage Act of 1857. Because it was widely used in Europe, the Americas, and the Far East, it became the first world currency by the late 18th century. The real de a ocho, also known as the Spanish dollar, the eight-real coin, or the piece of eight (Spanish peso de ocho) is a silver coin, of approximately 38 mm diameter, worth Eight Reales, that was minted in the Spanish Empire after 1598. Its purpose was
to correspond to the German Thaler.
Millions of Spanish dollars were minted over the course of several centuries. They were among the most widely circulating coins of the colonial period in the Americas, and were still in use in North America and in South-East Asia in the 19th century.