Parking is now available at the Ronald Reagan Presidential Library. Visitors are still placing flowers at the base of the hill and up at the library itself, but if you persevere, parking spaces open up -- one here and two there and, later in the day, a whole bunch. It's not yet as it once was and not yet what it will be again, but the frenzy has abated, and soon the warmth of sentiment will give way to the cold judgment of history. This is where Reagan is buried, but his place in history is still unknown.

Reagan's is the second presidential library I've visited this year. In the spring I drove up the Hudson Valley to Franklin D. Roosevelt's home at Hyde Park -- an odd coincidence since Reagan is now being likened to FDR. Reagan was as great a president, some are saying, and his likeness ought to replace Roosevelt's on the dime, the people's coin. A visit to their respective presidential libraries provides some perspective on this debate.

Much of the Reagan library is dedicated to the late president's acting career -- movie posters and costumes and publicity shots. That hardly disqualifies him as a great president, but it suggests that much of his popularity rests on his intrinsic appeal. He was a good-looking guy with a terrific smile and a winning personality. That was not all there was to Reagan, of course, but the rest does not bespeak historical greatness -- something else, something less.

Tour the FDR library and you will be reminded of all that Roosevelt accomplished -- the New Deal, above all. This, to me, is his claim to greatness. Any American president could have won World War II. The allies were bigger and stronger and more populous. Roosevelt was a terrific wartime president, but while any other man might not have done as well, the United States still would have emerged victorious.

The Great Depression was a different matter. Here FDR was the indispensable man. It wasn't that his alphabet soup of new government agencies -- WPA, CCC, etc. -- restored prosperity (World War II did that). It was that by creating those agencies, by putting people to work, by expanding welfare, by moderating the inherent cruelty of winner-take-all capitalism, he saved capitalism itself. FDR did that. Another president might not have.

The Reagan accomplishment, celebrated throughout his library, was the ending of the Cold War. Doubtful. Reagan may have accelerated the collapse of the Soviet empire, but it was crumbling anyway. I give Reagan his due. But he was not the indispensable man in this regard -- maybe Mikhail Gorbachev was -- and while another president might simply have treaded water and eschewed calling a spade a spade (the "evil empire"), the Soviet Union still would have collapsed sooner or later. With Reagan it was sooner.

I am not belittling Reagan's achievement. It was substantial. But it does not rise to the level of greatness. A great leader is indispensable. Without Washington, the colonies might not have won the Revolutionary War. Without Lincoln, the Union might not have been preserved. These men were indispensable to the history of their times -- and our own as well.

None of that sense of indispensability is evident in the Reagan library. Instead, what comes across is niceness, authenticity, immense communication skills, and strong ideological and personal values. Reagan did reverse the direction of government growth and he did lower taxes and he did break the air controllers' strike -- a historic accomplishment, you would think from the display here. During Reagan's terms the economy prospered and a slightly smaller share of it went to feed the government. That's not chopped liver, but it's not greatness either.

Oddly, the modern-day president who may satisfy the requirement of indispensability is the current one, George W. Bush. Simply stated, he made the war in Iraq happen. If Bush's vision of a transformed Middle East materializes, if terrorism is vanquished as a result, then he will have put his shoulder to history and swung it on its hinges. I don't think that will occur, but if it does, the Bush library will surely be worth a visit.

Standing before the Reagan library, I imagined the cars of average visitors pulling out -- and historians pulling in. As the historians have done with JFK, they will distinguish between popular and great, celebrated and indispensable -- and judge Reagan not partially by the mood of our times (anxious, uncertain) but totally, by his actual achievements. For now, let's leave Reagan to history. At the very least, I'm sure, it will treat him kindly.

cohenr@washpost.com