America has almost 12 million illegal immigrants.

Many of them came here on visas and never left.

But about 60 percent of them walked in from just one country — Mexico.

Though the stalled Obama Economy has caused about 900,000 to go home since 2007, there are still about 6 million Mexicans living in the United States who’ve sneaked across our borders.

Everyone from Marco Rubio to John McCain and our golfer in chief are trying to figure out how to deal with the illegal immigrants we have already and prevent future waves of Mexican migrants.

But no one seems to be talking about why so many Mexicans risk so much — including their lives — to break into America.

What is it that makes so many of them leave their families and children behind and travel — often on foot — to seek economic opportunity in the USA?

I’ve been to Mexico on business and on vacations. It’s a beautiful country, rich with oil, gas and other natural resources. It’s blessed with 114 million good and hardworking people.

Mexico has everything it needs to be a First World country. But it’s cursed.

Its government is corrupt and inept — and always has been. Now its federal government is a running joke. Its unable — and unwilling — to stop illegal drugs or people from crossing into the USA.

Mexico has become one of the most dangerous places in the world. Deadly criminal cartels effectively control the U.S.-Mexican border, trafficking in drugs and humans. Drug violence is so widespread that some cruise ships no longer visit Mexico’s Gold Coast.

No wonder so many Mexicans come north to a country where good jobs are plentiful, the wages are high and the streets are safe. If I were a Mexican, I’d be leaving too.

Yes, as Republicans say, it’s time to protect our borders better. Yes, it’s time to come up with realistic ways to deal with the illegal immigrants we already have living among us.

But it’s also time for one of our so-called political leaders to ratchet up the rhetoric and pull a Ronald Reagan.

When the Soviet Empire still controlled half of the world, my father stood near the Berlin Wall in 1987 and famously told Mr. Gorbachev that if he was really for peace, prosperity and liberalization, he should “Tear down this wall!”

It was a bold and masterful political move that showed the whole world that Ronald Reagan and the United States stood steadfastly on the side of freedom in the waning days of the Cold War.

One of our most important wars today — and one we clearly are not winning — is the drug war on our southern border.

What we need now is for President Obama to skip the back nine at the Floridian, go down to our border with Mexico and deliver a message to Mexican president Enrique Pena Nieto.

“Senor Nieto,” our part-time president should say, “End the corruption. Crush the drug cartels. Make Mexico a peaceful and safe society. Free your economy from the shackles of socialism so your citizens can go back home to prosper.”

President Obama also should declare to the world the United States is ready to do everything it can to help Mexico become a land of freedom and opportunity, not a land of fear and corruption.

Turning Mexico into a better place for its citizens to live and work — a place more like Canada, for example — would also do a lot to solve our future immigration problems.

Mexicans would stay home. And we wouldn’t need an army of border control agents and a 20-foot fence protecting our southern border any more than we need them on our northern border to protect us from illegal Canadians.

Michael Reagan is the son of President Ronald Reagan, a political consultant, and the author of “The New Reagan Revolution” (St. Martin’s Press). He is the founder of the email service reagan.com and president of The Reagan Legacy Foundation.