Answer: advance Spanish colonization
Explanation: The main purposes of the Spanish mission system in the Americas were to advance both Catholicism and the Spanish colonization which gave Spain a toehold in the frontier land. The missions were established during the 16th to 19th centuries by the Spanish empire they flanked the entirety of the Spanish colonies.
It is worthy to note that the conversion of the region was deemed crucial for the colonization of it and while the Spanish Crown controlled the political, economic, and social aspects of the region, the Catholic Church dominated the religious and spiritual aspects.
With this, the empire was able to extract gold and silver from the Americas, help stimulate the Spanish economy and ultimately made Spain a more powerful country.