The first of these to break away and form its own municipality was Capulhuac in 1827, with the community of Tlaltizapán joining Capulhuac shortly thereafter. Almoloya del Río, Santa Cruz Atizapán, San Mateo Texcalyacac and San Pedro Techuchulco were separated by the state legislature in 1847 to form the municipality of Almoloya del Rio. Santa María de la Asunción Xalatlaco separated in 1872. The community of Tianguistenco was officially declared a town in 1878 with the formal name of Tianguistenco de Galeana. San Nicolás Coatepec and San Lorenzo Huehuetitlán were added to the municipality in 1857 and 1863 with Tlaltizapán returning in 1891.