POCANTICO HILLS, N. Y.—Some might say David Rockefeller, a scion of America’s greatest fortune and the veteran chief executive of Chase Manhattan Bank, was a dedicated networker long before the age of Facebook.

That would grossly understate his horizons. Mr. Rockefeller recorded contact information along with every meeting he had with about 100,000 people world-wide on white 3-by-5-inch index cards. He amassed about 200,000 of the cards, which filled a custom-built Rolodex machine. He kept the 5-foot high electronic device at his family’s suite of offices in New York City’s Rockefeller Center for about half a century.

“In the annals of CEO history, the breadth and depth of this record of contacts stand out,’’ said Nancy Koehn, a Harvard business professor and historian. “This is a man with a large, long reach.’’

Mr. Rockefeller’s legendary Rolodex was a closely guarded trove of information. Now, nearly nine months after his death at 101—and long after many of his contacts have also died—The Wall Street Journal got a private peek.

Overall impression: The Rockefeller Rolodex collection embodies the ultimate expression of communication in the analog age. It provides a unique time capsule of modern history, both idiosyncratic and revelatory.