Michael Hertz, whose design firm produced one of the most consulted maps in human history, the curvy-lined chart that New York City subway riders peer at over one another’s shoulders to figure out which stop they want, died on Feb. 18 in East Meadow, N.Y. He was 87.

His son Eugene announced the death, at Nassau University Medical Center, but did not give a cause. Mr. Hertz also lived in East Meadow, on Long Island.

In the mid-1970s the Metropolitan Transportation Authority gave Mr. Hertz’s firm, Michael Hertz Associates, the task of coming up with a map of the New York City subway system that would help riders make sense of that many-tentacled beast.

There was already a system map (or “diagram,” as some preferred to call it), a colorful Modernist thing created by the Italian designer Massimo Vignelli and introduced in 1972. It was fun to look at — the Museum of Modern Art in New York has that version in its collection — but few users loved it, in part because the Vignelli map didn’t relate the underground to the aboveground.