Santa María del Río is one of the 58 municipalities located in the southern part of the Mexican state of San Luis Potosí. It is situated approximately 48 kilometers east of the city of San Luis Potosí and covers a land area of 1,655 square kilometers.
The municipality has a population of 37,290 inhabitants, with 12,000 people residing in the town of Santa María del Río as of 2005. The area is notably famous for its textile production, specifically serving as the cradle of the blue and white rebozo de bolita. It is also a primary location where the Rebozo Caramelo is woven.