A governor's mansion is often the last stop for politicians who plan to move into the White House. Before Barack Obama was elected president of the United States, four of his last five predecessors had been governors. Executive experience at the state level informs individual presidencies, and, as Saladin M. Ambar argues, the actions of governors-turned-presidents changed the nature of the presidency itself long ago. "How Governors Built the Modern American Presidency" is the first book to explicitly credit governors with making the presidency what it is today.

By examining the...