The presidency is a special office. Along with the vice president, the victorious candidate is our only nationally elected official, and the position has come to symbolize American government worldwide. In many ways, the office is greater than the people who have occupied it. In the 200-plus years of our nation's history, the presidency has grown and evolved dramatically. With the exception of Abraham Lincoln and Andrew Jackson, the nineteenth-century office holders exerted little executive power and mostly deferred to Congress on domestic affairs. Teddy Roosevelt began to change all that,...