Despite what you might have heard, Washington, D.C., was not built on a swamp. The myth has persisted in part because summers here are so oppressively humid. But the swamp Donald Trump promised in 2016 to drain was a metaphorical one; he cast the nation's capital as a fetid morass of corruption and self-dealing where insiders gobble up taxpayer dollars and twist the government's functions to their own nefarious ends. He didn't have to work very hard to convince people that's what it was.

So as the 2016 campaign came to a close, Trump promised again and again that he would drain that swamp, but without going into any detail. There were questions he might have answered, such as: What really goes on in the swamp? What is it about the swamp that's most problematic? How will you go about the draining of which you speak?

Of course, Trump never bothered with such details. And anyone who believed him could have done so only because they didn't understand the Washington swamp, and they didn't understand Trump.

Ordinary people may not pay a great deal of attention to politics, but they know that this thing called "Washington" is messed up. It's corrupt! It's mired in gridlock! It's wasteful! It can't get anything done! They're certain all that is true, even if they'd be no less able to explain the details than Trump.

But here's the real truth. Is there corruption in Washington? Sure. But it's actually far less corrupt today than it was in times past — the old-fashioned, briefcase-full-of-cash kind of corruption is almost totally absent. If you're looking for that kind of illegal activity, you're more likely to find it at the state and local level, where there's much less media scrutiny and laws tend to be less strict.

But the scandal, it's said, is what's legal. Which is absolutely true. Because of the Citizens United decision — hailed as a victory for liberty by Republicans — billionaires can pour money into races for every office, with almost no public disclosure of who's paying the bills. Huge corporations with teams of lobbyists make sure that government contracts and laws on things like taxes are written to maximize their profits. Too often the interests of citizens who don't wield that kind of power are ignored.

But only someone with the reasoning power of a turnip could have thought that Donald Trump would do anything about it. Was anyone really surprised when he appointed a bunch of billionaires to his Cabinet, or when he insisted that he didn't have to give up his business interests, or when he put his family members in influential positions in the White House, or when he decided to keep the logs of who meets with him and his staff secret, or when he signed a bunch of executive orders making life easier for big corporations? Will anyone be surprised when he tries to undo regulations on Wall Street, or tries to cut taxes for the wealthy?

And it goes even deeper. It isn't just that Trump wasn't sincere in his desire to make Washington more responsive to the public (though he wasn't). It's also that for a president to make a truly meaningful impact on the kinds of Washington habits and mores that people object to, he'd need extraordinary political skills. He'd have to be able to convince lawmakers to get beyond their individual interests to pass reforms that might threaten their livelihoods. He'd have to have a deep understanding of the workings of the executive branch so he could figure out why things work the way they do, what should and shouldn't be changed, and how you'd go about it. We may never have had a president less possessed of that skill and knowledge than Trump.

Because if you want to change government, you first need to understand government. Trump doesn't, and he doesn't seem to care enough to learn.

But in fairness, he probably would have failed even if he tried. You might remember that when Barack Obama took office he banned anyone who had been a registered lobbyist from working in his administration (though he ended up making some exceptions). Did that change the way Washington worked in any lasting way? Not really. Obama's administration was remarkably free of scandal, more so than any in decades. But that didn't make future scandals any less likely.

The deepest problems in the ways Washington works were built over decades and can't be undone by one president, whether he's an "outsider" or not. Dwight Eisenhower warned us about the military industrial complex in 1961; over half a century later, it's stronger and more deeply embedded than ever. Trump jawbones a couple of CEOs about the cost of government contracts and comes away thinking he's accomplished something; the CEOs, who know the system better than he ever will, understand how wrong he is.

If nothing else, Trump understands how fervent the desire to drain the swamp is — it's always there and it never abates. Much of the time it just means "My side isn't getting what it wants;" you didn't hear Republicans complaining about how Washington works when George W. Bush was starting wars and cutting taxes on the wealthy. But the desire is why every congressional challenger says, "If you elect me, I'm going to change the way they do business in Washington!" Which of course a freshman member of Congress will never do.

But a president probably won't do it either — especially this one.