Elk Rock State Park in Marion County, Iowa, occupies both upstream banks of Red Rock Reservoir between Knoxville and Pella, including its main section and the Mile Long Bridge area. Human presence in this landscape extends back about five thousand years, and in 1842 the Sac and Fox tribes granted white settlers rights to the grounds. The area was transformed by construction of Red Rock Dam from 1960 to 1969, which created the reservoir and submerged the extinct town of Red Rock. Land leased in 1978 became the present park, now a center for camping, boating, swimming, fishing, horseback riding, and wildlife observation.