The largest municipality by population in Guanajuato and third largest in Mexico is León, with 1,721,215 residents or approximately 27.9% of the state population.[1] The smallest municipality by population is Atarjea with 5,296 residents.[1] The largest municipality by land area is San Felipe which spans 3,014.92 km2 (1,164.07 sq mi), and the smallest is Pueblo Nuevo which spans 60.05 km2 (23.18 sq mi).[2] The first state constitution, Constitución Política del Estado Libre de Guanajuato, resulted in the formation of the first 17 municipalities in Guanajuato on April 15, 1826.[6][4] The newest municipality is Doctor Mora, incorporated on September 22, 1935.[7]