Costilla is a census-designated place in Taos County, New Mexico, United States. Its population was 205 as of the 2010 census. Costilla has a post office with ZIP code 87524. New Mexico State Road 196 and New Mexico State Road 522 intersect in the community.Costilla is located at 3658?43?N 10532?07?W? / ?36.978643N 105.535269W? / 36.978643; -105.535269. According to the U.S. Census Bureau, the community has an area of 3.056 square miles, all of it land.