Donald Trump arrives for a campaign rally in Green Bay, Wisconsin (Photo by Scott Olson/Getty Images)

Ladies and gentlemen, the Republican nominee has gone too far.

Yes, he has insulted women, Muslims, veterans, women, Mexicans, women, immigrants, women, locker rooms, Gold Star families, women who accused him of sexual assault, African Americans, our allies, fellow Republicans, the media, microphones, and the American election system, among others.

But his fact-free campaign has reached a new pinnacle when, on Monday evening at a Wisconsin rally, he called to “drain the swamp” of D.C., followed by the introduction of the new hashtag #DrainTheSwamp.

Referring to the District as a swamp is just as ahistorical as Trump saying he opposed the Iraq War.

As we pointed out back in 2007, historians have handily dismissed the notion that D.C. was uniquely built atop a swamp. This, from a popular historians’ listserv back in 2001, explains:

For the past ten years a number of historians of Washington, DC, have been trying to put to rest the idea that the city was built on a swamp. The Mall in particular was not a swamp, though it did have a river with a tidal flow next to it (where today’s Constitution Avenue runs) …

The City of Washington, like every other US city founded in the 17th and 18th centuries along tidewater, did have low ground. But the knee jerk association of Washington with a swamp, on a list on urban history, does a disservice, unless we all want to join forces and begin talking about the New York swamp, and the Philadelphia swamp, and the Baltimore swamp, etc. It bears remembering that to many Europeans in the 18th century all of America was a swamp.

Indeed, only about 2 percent of the city’s original boundaries fit the definition of a swamp, according to this Washington Post piece entitled “No, D.C. isn’t really built on a swamp.”

Certainly, the weather here can feel swamp-like, and the myth lends itself to rhetorical flourishes, but, like so much of what comes out of Trump’s mouth, it’s simply not true.

Plus, it continues the horrible tradition of confusing the federal government with the entire District of Columbia, where more than 600,000 people call home—think former Gov. Mike Huckabee (remember him?) calling to burn down D.C., or Iowa Representative Rod Blum calling for a recession in the city.