Frederick Louis Rath Jr., died peacefully in his sleep on April 1, 2001. He was born May 19, 1913, to Frederick L. Rath Sr., and Adeline Kolkebeck in Brooklyn, New York, where he graduated from Manual High School. He went on to graduate from Dartmouth in 1934 and Harvard University in 1936 with degrees in American history.

History became for him not only a profession but also a lifelong passion, and he was one of the first in this country to specialize in the emerging field of historic preservation. His earliest experience in this arena began with the National Park Service where he served at various historic sites, including Morristown, New Jersey, Fort Pulaski, South Carolina, and Vicksburg, Mississippi. In World War II, he served four years with the American Field Service in Syria and North Africa (2nd New Zealand Division and British 8th Army) and with the U.S. Army in Europe (Military Intelligence: Order of Battle, 21st and 28th Airborne Corps). After the war, he held a joint appointment as historian at the home of Franklin Delano Roosevelt and the Vanderbilt Mansion in Hyde Park, New York.

In 1946, he married Ann Richardson in Jeffersonville, Indiana, beginning a 54-year partnership that would produce two sons and a career he was always proud to declare would not have been possible without the love and support of his wife. In 1948, he became executive secretary of the National Council for Historic Sites and Buildings, which sought to reorganize under Congressional Charter as the National Trust for Historic Preservation. Upon presidential approval of the charter in 1949, he became the first director of the National Trust for Historic Preservation, and served in that capacity until 1956. He then became vice director of the New York State Historical Association in Cooperstown, New York, and adjunct professor for the Cooperstown Graduate Program in History Museum Training. In 1972, he assumed responsibility for the historic preservation program in New York State as a deputy commissioner in the Office of Parks, Recreation, and Historic Preservation, setting up a comprehensive program for all state historic sites and landmarks. Between 1979 and 1987 he became chief executive officer of Eastern National Park and Monument Association, a nonprofit educational organization he helped found, which, in cooperation with the Park Service, was dedicated to the development, publication, and dissemination of interpretive materials throughout the park system.

In addition to his role with Eastern National Park and Monument Association, he was a founding member of the American Association for State and Local History, and subsequently served on the board of directors of both organizations. In 1968, he was appointed to the Governor's Advisory Committee on Historic Preservation in New York State and was Chairman from 1971 to 1972. He also served on the New York State Board for Historic Preservation, 1979–85, and was a trustee emeritus for the Hancock Shaker Community and the Planting Fields Foundation. He was editor of New York State Historical Association and its Museums: An Informal Guide and co-editor of the six-volume Bibliography of Historical Organization Practices (1975–84). In addition to many other reports and publications, he also wrote Franklin D. Roosevelt's Hyde Park.

His awards include a Bronze Star medal, the Conservation Service Award of the U.S. Department of Interior, an honorary Doctor of Humane Letters degree from the State University of New York, the National Trust's Crowninshield Award, the Honor Award of the New York Parks and Conservation Association. He was perhaps most proud of his record of community service in Cooperstown, New York, which included chairing the Cooperstown Planning Commission and helping to develop the first comprehensive plan for the village he loved.

He is survived by his wife Ann Richardson Rath of Cooperstown, New York; his son William Rath of Cooperstown; his son David Rath, his daughter-in-law Michelle, and his granddaughter Mikaela of Williston, Vermont; his sister-in-law Ruth Frederick of Carmel, Indiana; his nephew David Frederick of Indianapolis, Indiana; his nephew John Skeats of Woodstock, New York; his niece Suzanne Graupner of Wilton, Connecticut; and several grandnieces and grandnephews.

—David Rath