county, extreme eastern South Carolina, U.S. It is a low-lying area on the Coastal Plain bordered to the southeast by the Atlantic Ocean, to the northeast by North Carolina, and to the west by the irregular curve of the Lumber, Little Pee Dee, and Great Pee Dee (Pee Dee River) rivers. The area along the Atlantic coast features the unbroken white sand beaches of the Grand Strand and its resort cities and towns. Within this region are Myrtle Beach State Park, Myrtle Beach Air Force Base, and the Intracoastal Waterway, which joins the Waccamaw River at its southern end. Inland the county's relief remains largely flat, with swamps along the rivers. Forests, predominantly of lowland hardwoods, cover most of the area.

In the 17th century the region, then inhabited by Siouan-speaking Indians, became the site of rice and indigo plantations separated from other colonial settlements by dense swamps. As late as the early 18th century, pirates (piracy)—including the notorious Blackbeard—infested the secluded inlets near Little River. Horry county was established in 1801 and named for Peter Horry, an officer in the American Revolution. Coastal Carolina University (founded 1954) is located in Conway.

The farms are among the state's most productive (tobacco, hogs, soybeans, and corn 【maize】). Lumbering, the textile industry, health care, and, especially, tourism and recreation are the basis of the economy. Conway is the county seat, and Myrtle Beach is the largest city. Horry has the largest area of any county in the state. Area 1,134 square miles (2,936 square km). Pop. (2000) 196,629; (2007 est.) 249,925.