Richard Gilder, a billionaire investor and benefactor who was instrumental in revitalizing two neglected exemplars of American democracy — the study of American history and Central Park — died on Tuesday at his home in Charlottesville, Va. He was 87.

His wife, the actress Lois Chiles, said the cause was congestive heart failure.

Mr. Gilder, a conservative, pro-growth Republican, formed an unlikely partnership in 1974 with George Soros, the liberal philanthropist, to rehabilitate Central Park, laying the foundation for what became the Central Park Conservancy in 1980.

Embraced by New York City’s parks commissioner at the time, Gordon J. Davis, the conservancy, a public-private partnership, restored Central Park, transforming it from a dust bowl that had been doomed by deferred maintenance during the city’s fiscal crisis of the 1970s to the 840-acre people’s oasis that was envisioned when it opened in the 19th century.

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He began his history restoration project in the late 1980s, teaming up with Lewis E. Lehrman, who had left academia to run Rite-Aid, his family’s drugstore chain, and had run for governor in 1982 as the Republican-Conservative candidate, barely losing to Mario M. Cuomo. They amassed a collection that would eventually consist of 70,000 original documents, letters, pamphlets, diaries and other primary sources that illuminate American history.

They then deposited them in a specially built $1 million vault in the basement of the New-York Historical Society in Manhattan to exhibit and share with scholars and educators.

They incorporated the collection into the Gilder Lehrman Institute of American History, which they established in 1994 to promote research, teacher training, exhibitions and classroom curriculums and endow prizes to encourage research in the names of Lincoln, Washington and Frederick Douglass.