John M. Blum, an influential historian of the American presidency whose 1954 biography of a maligned Theodore Roosevelt was pivotal in establishing the 26th president’s reputation as one of the country’s great chief executives, died on Monday at his home in North Branford, Conn. He was 90.

His death was confirmed by his son, Thomas.

Professor Blum, who taught at Yale from 1957 until 1991, was the author or editor of 18 books, almost all of which explored in some way the personalities and circumstances that drove political leaders to become agents of progressive social change, even when, like Roosevelt, they were heirs to wealth rooted in the American status quo.

He wrote extensively about the presidencies of Woodrow Wilson, Theodore Roosevelt and Franklin D. Roosevelt, and his immersion in the diaries and personal papers of his subjects gave his work a texture and level of detail that could dazzle fellow scholars — and sometimes drive away more casual readers. He never wrote a best seller.

But he was one of four scholars, along with Arthur M. Schlesinger Jr., James MacGregor Burns and Frank Freidel, who pioneered the study of the American presidency in the 20th century, said David M. Kennedy of Stanford, a Pulitzer Prize-winning historian and a former student of Professor Blum’s....