Auburn Valley State Park in Yorklyn, Delaware, unites open space, industrial heritage, and the former Marshall family estate along Red Clay Creek. Built through conservation efforts that accelerated around 2000, the park grew from Auburn Heights Preserve as the state acquired former company land, donated Marshall property, and other parcels before establishing the park in 2008 and renaming it in 2018. Its centerpiece is the 1897 Auburn Heights Mansion above the Marshall mills and Yorklyn, while the Marshall Steam Museum preserves an operating collection of steam and electric vehicles. Trails, the miniature Auburn Valley Railroad, and the Oversee Farm unit extend its historic and natural landscape.