John A. Farrell, the author of “Richard Nixon: The Life,” has been named the winner of the New-York Historical Society’s Barbara and David Zalaznick Book Prize, awarded annually to the best work in the field of American history or biography.

The book, published by Random House, drew headlines for Mr. Farrell’s discovery of notes confirming Nixon’s meddling, during the 1968 presidential campaign, in President Johnson’s peace efforts in Vietnam. More broadly, Jennifer Senior, reviewing the book in The New York Times, praised its subtle exploration of Nixon’s complex relationship with race and other aspects of his paradoxical character — “the spikier stuff,” she wrote, “that distinguishes real-life sinners from comic-book villains.”

The prize, which is named in honor of the philanthropists Barbara and David Zalaznick, carries a $50,000 cash award, along with the unofficial title “American historian laureate.” (The historical society, unlike the Library of Congress, which designates the United States poet laureate, is a private organization.) Past winners include Jane Kamensky, Drew Gilpin Faust, Eric Foner and Gordon S. Wood.

Mr. Farrell, a journalist who has also written books about Clarence Darrow and Tip O’Neill, has not been shy about drawing parallels between the Watergate scandal and the current investigation into possible ties between the Trump campaign and Russia. In a statement he was less direct, naming no names but saying that journalists and scholars have been called on to defend the study of history, and “the concept of truth itself,” from “corrosive attack.” ...