The missions became important religious, cultural, commercial, and military centers. As more Native Americans adopted the Spanish way of life and Catholicism, they were trained in various trades such as carpentry, iron working, and weaving. They also worked in the fields growing crops and raising livestock including sheep, goats, and cattle. Cattle ranching became a profitable enterprise and it was here that cattle ranching in the United States was developed. The missions were most successful between 1745-1775. By 1780, the number of people living at the missions had begun to decline as a result of intermarriage, disease, and acculturation. In other words, there was no longer much need to convert Native Americans.
Efforts to preserve the missions began in the 1920s. In 1975, Mission Parkway was established as the original name of the historical park. It was named as the San Antonio Missions National Historical Park in November of 1978, containing 84 historic places all down the San Antonio River and the south side of the city. The park is also a UNESCO World Heritage site