The Maria Theresa thaler (MTT) is a silver bullion-coin that has been used in world trade continuously since it was first minted in 1741. It was named after Empress Maria Theresa, who ruled Austria, Hungary, and Bohemia from 1740 to 1780. In German-speaking countries, following a spelling reform dated 1901 which took effect two years later, "Thaler" is written "Taler" (although the spelling of "Theresia" was not affected because of Greek origin). Hence 20th-century references to this coin in German and Austrian sources are found under "Maria-Theresien-Taler". The spelling in English-speaking countries was not affected.
Since 1780, the coin has always been dated 1780. On September 19, 1857, Emperor Francis Joseph of Austria declared the Maria Theresa Taler to be an official trade coinage. A little over a year later, on October 31, 1858, the Maria Theresa Taler lost its status as currency in Austria.
The following mints have struck MTTs: Birmingham, Bombay, Brussels, London, Paris, Rome and Utrecht, in addition to the Habsburg mints in Günzburg, Hall, Karlsburg, Kremnica, Milan, Prague and Vienna. Between 1751 and 2000, some 389 million were minted. These different mints distinguished their issues by slight alterations to the saltire, or flower symbol, which looks like an X, at the top left of the reverse side of the coin. In 1946, the Vienna Mint rescinded any rights of foreign governments to issue such copies; subsequently, the Vienna Mint has produced over 49 million MTTs.
The MTT came to be used as currency in large parts of Africa until after World War II. It was common from North Africa to Somalia, Ethiopia, Kenya, and down the coast of Tanzania to Mozambique. It could also be found throughout the Arab world, especially in Saudi Arabia, Yemen and Muscat and Oman, and in India. During the Japanese occupation of Indonesia in World War II, enough people preferred it to the money issued by the occupying forces that the American Office of Strategic Services created counterfeit MTTs for use by resistance forces.
It was one of the first coins used in the United States and probably contributed, along with the Spanish dollar, to the choice of a dollar as the main unit of currency for the United States.