George B. Hartzog Jr., a former director of the National Park Service who led an unprecedented expansion of the nation's system of parks, wildlife refuges and historic sites, and who helped secure passage of the National Historic Preservation Act in 1966, died June 27 at Virginia Hospital Center of complications from diabetes and kidney disease. He was 88 and lived in McLean, Va.

Hartzog used charisma, political savvy and deep knowledge of the nation's park system to increase the scope of Park Service programs and to raise their popularity. He added more than 70 new areas to the Park Service, totaling 2.7 million acres, and helped double attendance at the nation's parks and historic sites.