Auburn Valley State Park, State park with steam museum in New Castle County, US

Auburn Valley State Park is a woodland and meadow park in New Castle County, Delaware, set along the Red Clay Creek and featuring historic buildings on its grounds. Among these is a Victorian mansion and a museum devoted to steam-powered vehicles and the early days of motorized travel.

The mansion on the grounds was built in 1897 by Israel Marshall and stayed in the family for over a century before the state of Delaware took ownership in 2008. The steam vehicle collection was assembled separately and represents a short but formative period in the history of the car.

The Marshall Steam Museum holds a collection of working Stanley Steamer cars, which are among the few still operable examples of their kind. Visitors can get close to these rare vehicles and see how early engineers approached the challenge of powering a car without a gasoline engine.

The mansion and museum can only be visited on guided tours, while the hiking and biking trails on the grounds are open every day. A small coal-powered train runs around the property during special events held at various times of the year and offers rides to visitors.

The collection was started by T. Clarence Marshall, a licensed Stanley dealer, and first opened to the public in the 1970s. It is housed in the Auburn Heights carriage house, where volunteers keep the cars running, and it includes a 1/8-size steam locomotive, the Auburn Valley Railroad, circling the estate.