Welcome, ladies and gentlemen, to the wild and wacky world of Donald Trump. Today, we'll be taking a look at one of his favorite talking points -- illegal immigration, particularly from Mexico.

Apparently, it is a HUUUUGE issue. According to Trump, there are over 30 million illegal immigrants in the U.S. right now. Illegal immigrants are apparently like an "infectious disease" that "is pouring across the borders ... being pushed into the United States by the Mexican government." Trump has taken full credit for bringing up this huuuge issue, saying that it "wasn't a subject that was on anybody's mind until I brought it up at [his] announcement." And, fortunately, he has a solution: the Great Wall of Trump, which will be 30 feet high, or 45 feet high, or 65 feet high or something like that, and it will have a "big, beautiful door" and a "beautiful nice precast plank with beautiful everything. Just perfect." And apparently it won't cost us a cent, since Trump thinks Mexico will pay for the whole thing! What a deal!

But, of course, it's not that simple. Our tour of the Trumpland is over, so we have to come back to the real world.

There are between 11 and 12 million illegal immigrants in the United States, based on research by the Department of Homeland Security, the Center for Immigration Studies, the Migration Policy Institute and the Pew Research Center. And, contrary to popular belief, the vast majority of illegal immigrants actually do fill out government census forms because the forms are confidential and, if left unfilled, can trigger a friendly visit or six from government census bureau workers. When Trump was asked where he found the 30 million figure, he responded that he saw it "written in various newspapers," although it seems unlikely that those various newspapers trump the research estimates.

As for the "infectious disease pouring across our borders," it turns out the disease has been pouring the opposite direction that Trump implied over the last decade or so. Mexican illegal immigration has been dropping since its high point in 2007, and total illegal immigration rates have leveled off since then as well.

To be fair, it is possible that this could change as we transition out of the Great Recession, but that is unlikely since "undocumented migration stopped in 2008 and has been zero or negative since -- not because the economic fundamentals have changed, but because the fertility rate dropped from 6.7 births per woman in 1970 to 2.2 births today, bringing about an aging of the population ... People initiate migration between the ages of 18 and 30, and if they don't migrate then, they are unlikely ever to migrate," according to professor Douglas Massey at Princeton University.

Trump has blamed the Mexican government for illegal immigration, saying that it "forces many bad people into our country." However, researchers from the Mexican Migration Project and experts from the Center for Immigration Studies and the University of Chicago found not only that the Mexican government has no policy of forcing migrants to the U.S., but that most immigrants are driven by desire to work or join family already in the U.S.

Also, it turns out that Trump was not the only reason people are thinking about illegal immigration, since it has been a highly debated subject in the past several decades. Surprise! On Fox News Sunday, the subject was brought up the same amount before as after Trump's announcement: five times in seven shows the week before and five times in seven shows afterwards. On a broader scale, the terms "undocumented" and "illegal immigrant" were mentioned in major newspapers more often in the 51 days before Trump's announcement than the 51 days after.

Finally, when Trump suggested that Mexico pay for his wall, not one but two former Mexican presidents responded with a resounding "no." Felipe Calderon (Mexican President from 2006 to 2012) said "Mexican people - we are not going to pay any single cent for such a stupid wall." Vincente Fox (Mexican President from 2000 to 2006) went even further and said that "I am not going to pay for that f***ing wall. He should pay for it."

The wild and wacky world of Donald Trump is an absolutely fascinating place to study, but it has little in common with the one that the rest of us live in.

For more information on the subject of immigration, check out some of the following resources:

International Business Times, "Illegal Immigration 2015: Undocumented Immigrants Having Fewer Children In U.S."

Migration Policy Institute, "The Economics and Policy of Illegal Immigration in the United States"

TIME Magazine, "Psst: Illegal Immigration is Actually Declining"

And for more examples of Donald Trump lying to the American public, because some of these are honestly pretty silly, check out some of the following resources:

Donald Trump's PolitiFact File

PoliticusUSA, "Donald Trump Told So Many Lies Fact Checkers Couldn’t Pick Just One for Lie of the Year"

The Washington Post, "Donald Trump is Constantly Lying"