Harper is an unincorporated community and census-designated place (CDP), located 23 miles (37 km) 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 in western Gillespie County at 30°18′04″N 99°14′36″W (30.301009, -99.243326). This is about 84 miles (135 km) northwest of San Antonio and 101 miles (163 km) west of Austin.
According to the United States Census Bureau, the CDP has a total area of 56.6 square miles (146.7 km2), of which 56.6 square miles (146.5 km2) are land and 0.1 square miles (0.2 km2), or 0.14%, is covered by water. The headwaters of the Pedernales River flow through the community.
On December 15, 1847, a petition was submitted to create Gillespie County. In 1848, the legislature formed Gillespie County from Bexar and Travis Counties. While the signers were overwhelmingly German immigrants, names also on the petition were Castillo, Pena, Munos, and a handful of Anglo names.
The first white settlers were the families of Eli McDonald and Matthew Taylor in 1863. A historical marker just south of U.S. Highway 290 commemorates the McDonald massacre of August 1864.