Use outside Mexico
The 18th and 19th century Spanish dollar and Mexican peso were widely used in the early United States. On July 6, 1785, the value of the United States dollar was set by decree to approximately match the Spanish dollar. Both were based on the silver content of the coins.
The first U.S. dollar coins were not issued until April 2, 1792, and the peso continued to be officially recognized and used in the United States, along with other foreign coins, until February 21, 1857. In Canada, it remained legal tender, along with other foreign silver coins, until 1854 and continued to circulate beyond that date. The Mexican peso also served as the model for the Straits dollar (now the Singapore/Brunei Dollar), the Hong Kong dollar, the Japanese yen and the Chinese yuan. The term Chinese yuan refers to the round Spanish dollars, Mexican pesos and other 8 reales silver coins which saw use in China during the 19th and 20th century. The Mexican peso was also briefly legal tender in 19th century Siam, when government mints were unable to accommodate a sudden influx of foreign traders, and was exchanged at a rate of three pesos to five Thai baht.
Some establishments in border areas of the United States accept Mexican pesos as currency, such as certain border Walmart stores, certain border gas stations such as Circle K, and the La Bodega supermarkets in San Ysidro on the Tijuana border. In 2007, Pizza Patrón, a chain of pizza restaurants in the southwestern part of the U.S., started to accept the currency, sparking controversy in the United States. Other than in U.S., Guatemalan, and Belizean border towns, Mexican pesos are generally not accepted as currency outside of Mexico.