Potosí is a city and the capital of the department of Potosí in Bolivia. It is one of the highest cities in the world by elevation at a nominal 4,090 metres (13,420 ft) and it was the location of the Spanish colonial mint.

Potosí lies beneath the Cerro de Potosí—sometimes referred to as the Cerro Rico ("rich mountain")—a mountain popularly conceived of as being "made of" silver ore, which has always dominated the city. The Cerro Rico is the reason for Potosí's historical importance, since it was the major supply of silver for Spain during the period of the New World Spanish Empire.

The silver was taken by llama and mule train to the Spanish Main^{[citation needed]} whence it was then taken to Spain on the Spanish treasure fleets. Cerro de Potosí's peak is 4,824 metres (15,827 ft) above sea level.

Founded in 1546 as a mining town, it soon produced fabulous wealth, becoming one of the largest cities in the Americas and the world, with a population exceeding 200,000 people.

In Spanish there is still a saying, valer un potosí, "to be worth a potosí" (that is, "a fortune"). For Europeans, Peru—Bolivia was part of the Viceroyalty of Peru and was known as Alto Perú before becoming independent—was a mythical land of riches. Potosí appears as an idiom for "extraordinary richness" in Miguel de Cervantes' famous novel, Don Quixote (second part, cap. LXXI). One theory holds that the mint mark of Potosí (the letters "PTSI" superimposed on one another) is the origin of the dollar sign.

San Luis Potosí (Spanish pronunciation: [ˈsan ˈlwis potoˈsi]), officially Free and Sovereign State of San Luis Potosí (Spanish: Estado Libre y Soberano de San Luis Potosí), is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 58 municipalities and its capital city is San Luis Potosí.

It is located in North-Central Mexico. It is bordered by the states of Coahuila to the north, Nuevo León to the northeast, Tamaulipas and Veracruz to the east, Hidalgo, Querétaro, and Guanajuato to the south, Zacatecas to the northwest, and Jalisco to the west.

In addition to the capital city, the state's largest cities include Ciudad Valles, Matehuala, and Rioverde.

The state and its capital are both named after Louis IX of France (also known in Mexico as San Luis Rey de Francia, Saint Louis, King of France), its patron saint. The Potosí was added in reference to the fabulously rich mines of Potosí, Bolivia, believed to have enough gold to build a bridge between Bolivia and Spain. Thereafter, upon the development of Cerro de San Pedro near the capital city, they found such gold wealth that they compared it to that of Potosi and thus they named it as such. The wealth of these mines is thought to be comparable to that of the local mines at Cerro de San Pedro.