Following the adoption of the National Historic Preservation Act, the National Trust broadened in its mission beyond administering historic sites. In 1969, the National Trust created the Preservation Services Fund to provide financial assistance to local preservation projects. In 1971, the National Trust opened its first field office in San Francisco. As the organization grew, the National Trust expanded its work, consisting of programs, educational resources, and advocacy. In 1980, the National Trust initiated the National Main Street Center, specializing in revitalizing historic business districts, which has since transitioned into a subsidiary.