David and Mary Weeks's great-grandson, William Weeks Hall, lived in the house from 1922 until his death in 1958. He tried to preserve what remained of the property. He made a large garden of live oak, bamboo, camellias, azaleas, and other plants. He donated the house and garden to the National Trust for Historic Preservation at his death. The Trust has owned and operated Shadows until the present. Shadows-on-the-Teche was named a National Historic Landmark on 30 May 1974. 