Harper is a census-designated place (CDP), located 23 miles (37km) west of Fredericksburg on U.S. Highway 290, in Gillespie County, in the U.S. state of Texas. The population was 1,192 at the 2010 census. Harper is located at about 76 miles (122km) northwest of San Antonio and 90 miles (140km) west of Austin. According to the United States Census Bureau, the CDP has a total area of 56.6square miles (147Square kilometers), all of it land. On December 15, 1847, a petition was submitted to create Gillespie County. In 1848, the legislature formed Gillespie County from Bexar and Travis counties.