THE AMERICAN PRESIDENT:

From Teddy Roosevelt to Bill Clinton

By William E. Leuchtenburg

Oxford, 886 pp., illustrated, $34.59

Surely William E. Leuchtenburg, author of ‘’The Perils of Prosperity’’ and perhaps the preeminent scholar of the New Deal, will not object to being described as the Grand Old Man of American history. His output is indisputably grand, and at age 93 he is just as assuredly old. Born in Warren G. Harding’s administration, he is still writing at the end of Barack Obama’s.

The result is a leviathan of a book, ‘’The American President,’’ 886 pages long and rich in learned asides and lessons that undoubtably will prove useful as November heaves into view. It is also a publishing curiosity — the second of a two-part work, examining the presidency since Theodore Roosevelt, with the first volume still in production. It isn’t everyone who writes the concluding work first, but then again Leuchtenburg isn’t everyone — with his mastery of anecdote, his eye for the telling detail, and his entrancing narrative style, he is the historian for ­Everyman.

This volume, covering the 20th-century presidents, is organized chronologically, covering between one and three chief executives per chapter. He provides an excellent prologue, which skates briskly through the administration of William McKinley, whose presidency penetrates the first 20 months of the century, while offering an overview of the presidency that will evolve over the coming decades. And he concludes with a nine-page epilogue that provides a sweeping critique of the institution of the office and takes issue with his earlier conviction, explored in his 1969 “In the Shadow of FDR,’’ that the modern office began with Franklin Delano. He now believes its origins can be traced to Theodore Roosevelt.

Overall, this book is an inviting triumph: the erudition of a distinguished historian, the elan of a master craftsman, the accessibility of a popular writer.

That’s because in this work Leuchtenburg is willing to break several sacred tenets of his trade. He employs no footnotes, a sin in the corridors of the history departments of Columbia and Chapel Hill, where he taught generations of students. He violates the precept, so treasured in some academic circles, that history is seen only crudely through the lens of personality (and presidents). He quotes other historians promiscuously and even cites journalists (Tom Wicker, several times) and novelists (John Steinbeck, on the heavy burden of the presidency). The result is a joy to the reader for all the reasons it may be a horror for the scholar. Given his record of scholarly achievement, though, such sins can be forgiven.

His approach — more than a cursory survey — is evident in his trifecta chapter on the Republican presidents who filled the 1920s, forgettable or failed figures as they were. He paints Harding as a man “pathetically cognizant of his inadequacy’’; Calvin Coolidge as “a poor communicator not because he was silent but because he had so little to impart’’; and Herbert Hoover as a victim of his own early business and philanthropic success: “Seeing himself as a dispassionate engineer operating with the precision of a slide rule, he trapped himself in doctrine.’’

Leuchtenburg characterizes the three presidencies of the 1920s as a time when “the expansion of the presidency all but ground to a halt.’’ The only major change to the executive branch was the establishment of the Bureau of the Budget. Leuchtenburg makes the unfamiliar but unforgettable point that Coolidge and Hoover were nasty fellows in private. Perhaps the best quote of the book: Hoover’s reference to a senator as “the only verified example of a negative I.Q.’’

In this volume Leuchtenburg, who has defined FDR in the American pantheon, credits him for altering “the very nature of political discourse in the United States,’’ for fashioning “the only long-lasting realignment of the 20th century,’’ and for crafting “the template for how a modern chief executive was expected to perform.’’

These expectations shaped Harry Truman (“this ill-tempered, lackluster provincial’’ who would excel in foreign relations, civil rights, and would “leave a larger legacy of new institutions in the executive branch than any other president’’), Dwight Eisenhower (a popular president who “has fared even better with posterity than he did with his contemporaries’’), John Kennedy (“a negligible impact on the institution of the executive office’’), and Lyndon Johnson (a legislative magus who nonetheless “bears a large share of the blame for the devastation and loss of life’’ of Vietnam).

Leuchtenburg credits Richard Nixon for giving “history more than a nudge’’ and for playing a major role in moving the country “from credulity to cynicism’’ and argues that “little of consequence’’ took place in the Gerald Ford years. Jimmy Carter is dismissed, memorably, as “the village scold.’’

Page counts may be unreliable measures of presidential significance, but despite his disapproval of Ronald Reagan, Leuchtenburg devotes only five fewer pages (94) to him than to FDR (99). But in those pages he argues that Reagan “contributed nothing at all to the literature of statecraft, [and] offered false reassurance of the sort peddled by patent medicine salesmen.’’

He is not as approving of George H.W. Bush as Jon Meacham is in his new biography of the 41st president. He concludes with Bill Clinton, whose achievements he minimizes in comparison with his impeachment, a permanent stain on his record and legacy.

This tour de force of a tour d’horizon concludes with a stern warning about what he describes as “the dark underside’’ of our presidents: “Too often, they have wasted the lives of our children in foreign ventures that should never have been undertaken. They are both the progenitors and the victims of inflated expectations, and when they overreach, they need to be checked.’’ Plaster that over every fire hall in Iowa and every town hall in New Hampshire. And as the 2016 voting approaches, caveat emptor.

David M. Shribman, for a decade the Globe’s Washington bureau chief, is executive editor of the Pittsburgh Post-Gazette. He can be reached at dshribman@post-gazette.com.