The Bajío (lowlands) is a region of Central Mexico that includes the plains south of the Sierra de Guanajuato, in the state of Guanajuato, as well as parts of the states of Querétaro (the Valley of Querétaro) and Michoacán (particularly the area around Zamora).
In general parlance, it is usually associated with the States of Guanajuato and Querétaro, although it only forms a part of them. It is characterized by its highly mechanized agriculture, with mean precipitation in the order of 700 millimetres (28 in) per annum (one of the highest in the country). During the Viceroyalty of New Spain, the area was known as the breadbasket of the territory.
The Bajío is known for being one of the most conservative bastions of Mexican Catholicism.
The Bajío is where in April 1915, during the Mexican Revolution, General Álvaro Obregón provoked decisive battles against Pancho Villa. Villa's troops lost in June outside Celaya.
Recent archaeological studies of the Bajío have discovered an extensive, pre-historic cultural tradition unique to the region, particularly along the flood plains of the Lerma and Laja rivers. The Bajío Culture flourished from 300 to 650CE, with cultural centers ranging from El Cóporo in the far north of Guanajuato to Plazuelas in the far south west. More than 1,400 sites have been discovered throughout the state of Guanajuato, with only the sites of Cañada de la Virgen, El Cóporo, Peralta, and Plazuelas having received extensive study.