Jefferson Patterson Park& Museum is a 560-acre state park and museum located along the Patuxent River in St. Leonard, Calvert County, Maryland. The property of JPPM was given to the state of Maryland by Mary Marvin Patterson in 1983 in honor of her husband Jefferson Patterson, a U.S. diplomat. Many of its buildings were designed by Gertrude Sawyer starting in the 1930s, and some landscaping was done by Rose Greely and Cary Millholland Parker.