Presidents come and go, but monuments are always with us. There's a reason Theodore Roosevelt is the only 20th century President whose face is carved into Mount Rushmore, the only one who could hold his own with Washington, Lincoln and Jefferson. Roosevelt not only remade America, but he also charmed the pants off everybody while he did it. And just short of a century after he left the White House, in 1909, the collective memory of his strength and intellect and charisma still lingers. How many times over the years since have Americans settled their affections on some thoughtful, vigorous man who reminded them a bit of Roosevelt? What was Ernest Hemingway if not a later edition of Teddy, without the burden of office but still equipped with T.R.'s literate machismo? And who could look at John F. Kennedy, scrimmaging with his clan at Hyannis Port, and not be reminded of another young President, tussling with his kids at Sagamore Hill? Is it any surprise when more recent Presidents try to borrow a bit of his halo? Bill Clinton had Teddy's bust on his desk. George W. Bush let it be known that he spent last Christmas vacation reading a Roosevelt biography, his second since he got to the White House.

Teddy stays with us because he seems so much like one of us. Although he was born in 1858, it's the 20th century he decidedly belongs to, the century he brought America into on his terms. Roosevelt's years in the White House were one of those hinges upon which the whole of American history sometimes turns. When he arrived there, he already understood the energies that had been building in the U.S. for decades after the Civil War: the explosion of its industrial power, the ineluctable impulse to expand. He used his presidency to discharge those energies in ways that left the U.S. profoundly changed. Again and again, he framed the questions we still ask. How much influence should the government have over the economy? How much power should the U.S. exert in the wider world? What should we do to protect the environment? The answer he liked best--More--didn't satisfy everyone. It still doesn't. But anytime we offer our own, we know that we do it with him looking over our shoulders.

Where was his impact the greatest? Start with the economy. When Roosevelt first came to the presidency, after the assassination of William McKinley, the U.S. was emerging as one of the world's wealthiest nations. It was first in the world in its output of timber, steel, coal, iron. Since 1860 the population had doubled, exports had tripled. But that bounding growth had brought with it all the upheavals of an industrial age--poverty, child labor, dreadful factory conditions. Year after year, workers faced off against bosses with their fists clenched.

Roosevelt came to believe that government had the right to moderate the excesses of free enterprise. Although his exercises of power seem modest to us now--the breakup of monopolies, the Pure Food and Drug Act, the meat-inspection and industrial-safety laws--it was a shock to the system at the time. Roosevelt--a Republican!--insisted that one of the things government must govern is the economy. Today, when the Justice Department goes after Microsoft or Enron, when the Environmental Protection Agency adjusts mileage standards or the Fed tweaks the prime, somewhere his ghost is smiling....