Calvillo is a town an its surrounding municipality of the same name in the Mexican state of Aguascalientes. The town serves as municipal seat of the municipality. Calvillo is the second most populated city in the state, surpassed in importance only by the capital city. It is located to the western part of the state, at about 52 kilometers of the city of Aguascalientes. It stands at 21°51′N, 102°43′W in the southwestern corner of the state. It is bounded by Jalisco and Zacatecas. The municipality, which has an area of 931.26 km² (359.56 sq mi), reported a population of 50,183. The town of Ojocaliente is another significant community in the municipality. Calvillo is one of the richest, most prosperous municipalities in Aguascalientes.