SULPHUR, Okla. (AP) — The original portion of southern Oklahoma's Chickasaw National Recreation Area soon could be designated as a National Historic Landmark.

Park Superintendent Bruce Noble says the Landmarks Committee of the National Park Service's Advisory Board voted to recommend that the original "Platt National Park" portion of the park receive the historic designation.

If the advisory board votes next April to accept the recommendation, the U.S. interior secretary would be asked to formally approve the historic designation.

Noble says the portion of the park under consideration is considered significant because of its landscape, architecture and preserved environment. From 1933 to 1940, the Civilian Conservation Corps used native stone to build roads, trails and recreational areas and planted trees and shrubs in the park.

Only 20 National Historic Landmarks now exist in Oklahoma.