The illegal immigration problem is going away.

That's the conclusion I draw from the latest report of the Pew Hispanic Center on Mexican immigration to the United States.

Pew's demographers have carefully combed through statistics compiled by the U.S. Census Bureau, the Department of Homeland Security and the Mexican government, and have come up with estimates of the flow of migrants from and back to Mexico. Their work seems to be as close to definitive as possible.

They conclude that from 2005 to 2010, some 1.39 million people came from Mexico to the United States and 1.37 million went from the U.S. to Mexico. "The largest wave of immigration in history from a single country to the United States," they write, "has come to a standstill."

The turning point seems to have come with the collapse of housing prices and the onset of recession in 2007. Annual immigration from Mexico dropped from peaks of 770,000 in 2000 and 670,000 in 2004 to 140,000 in 2010.

As a result, the Mexican-born population in the United States decreased from 12.6 million in 2007 to 12.0 million in 2010. That decrease consisted entirely of Mexican-born illegal immigrants, whose numbers decreased from 7.0 million in 2007 to 6.1 million in 2010.

"Mitt Romney has been ridiculed for saying illegal immigrants should 'self-deport.' But that seems to be exactly what many of them have been doing." - Michael Barone Mitt Romney has been ridiculed for saying illegal immigrants should "self-deport." But that seems to be exactly what many of them have been doing. The U.S. government has been sending back more illegals lately, but most of the flow to Mexico has been voluntary.

The Pew analysts hesitate to say so, but their numbers make a strong case that we will never again see the flow of Mexicans into this country that we saw between 1970, when there were fewer than 1 million Mexican-born people in the U.S., and 2007, when there were 12.7 million.

One reason is that Mexico's population growth has slowed way down. Its fertility rate fell from 7.3 children per woman in 1970 to 2.4 in 2009, which is just above replacement level.

Meanwhile Mexico's economy has grown. Despite sharp currency devaluations in 1982 and 1994, its per capita gross domestic product rose 22 percent from 1980 to 2010.

Mexico, like the United States, experienced a recession from 2007 to 2009. But since then Mexico's GDP has grown far faster than ours: 5.5 percent in 2010 and 3.9 percent in 2011.

Mexico seemed yoked to the U.S. growth rate after passage of the North American Free Trade Agreement in 1993. But since the recession it seems yoked to the more robust growth rate of the state with the biggest cross-border trade, Texas.

An end to the huge flow of immigrants from Mexico has huge implications for U.S. immigration policy.

Because of our long land border with Mexico (the Rio Grande is a trickle most of the year), it has been far easier to immigrate illegally from Mexico than from any other country.

As a result, Mexican immigrants tend to be younger, poorer, less educated and less fluent in English than immigrants from other countries. They are also more likely to be illegal -- Mexicans are 30 percent of all immigrants but 58 percent of illegals -- and less likely to become U.S. citizens.

A continued standstill in Mexican immigration means the number of illegals in the United States will probably continue to decline, even in an economic recovery. Children of illegals born in the U.S., who are automatically U.S. citizens, don't add to the illegal numbers.

And no other country has produced or is likely to produce anything close to the number or share of illegals.

The central focus of the debate over the so-called comprehensive immigration bills, which came to the floor of the Senate in 2006 and 2007, was their provisions for legalization of those illegally here -- amnesty to opponents. On the campaign trail Barack Obama is promising to push for such legislation just as he promised in 2008.

But he didn't deliver when Democrats had supermajorities in both houses and is unlikely to get anywhere on this project in a second term.

It may not matter much. With the Mexican reservoir of potential illegals dried up, and with better border enforcement and increased use of the much improved e-Verify system in workplaces, the illegal population seems likely to decline.

The key immigration issue for the future is whether America, like our Anglosphere cousins Canada and Australia, will let in more high-skill immigrants.