Martin Dies Jr. State Park is a 705-acre Texas park on Steinhagen Reservoir in East Texas, at the northern edge of the Big Thicket near the meeting of the Angelina and Neches rivers. Opened in 1965 on land leased from the United States Army Corps of Engineers, it was first called Dam B State Park before being renamed that same year for State Senator Martin Dies Jr. Its reservoir setting and the meeting of wetland and forest ecosystems define both its recreation and natural character, supporting boating, fishing, camping, and stargazing along with diverse pine woods, cypress, broadleaf trees, and abundant wildlife.