Greenwell State Park in St. Mary’s County, Maryland, is a public recreation area on the Patuxent River that blends riverfront open space with historic farm buildings, including the Rosedale Manor House and the Bonds-Simms tobacco barns complex. It began in 1971 when John Phillip Greenwell Jr. and Mary Wallace Greenwell donated their 167-acre farm to Maryland for use as a public park, and the state later enlarged it by buying the adjoining 430-acre Bond property. The park’s trails, shoreline, and former farmland support many outdoor activities while preserving a strong connection to the region’s agricultural heritage.