Another one of the biggest and most significant causes of the Mexican-American War was the annexation of Texas. Mexico became an independent republic in 1821. At this time, Texas was one of 19 Mexican states and had a sparse population. To encourage additional settlement, just before independence the Spanish commandant general in Monterrey gave an American family, the Austins, permission to move about 300 American Catholic families to Texas (Mexican American War (Causes)). Stephen Austin received permission from Mexican authorities to bring into Texas as many as 300 families each year as long as they professed to be Catholics, learned spanish and agreed to live by Mexican law. Mexican authorities thought that the immigrants could be fully integrated