07/11/2014 10:26 am ET Updated Sep 10, 2014

The Children on the Rio Grande Have Families and They Are Here

Win McNamee via Getty Images

The Central American children fording the Rio Grande by the thousands each week this summer are heading to homes in the United States where parents and other relatives await them. They are not mindlessly fleeing crime and poverty. They are fleeing with a purpose and with a direction in mind.

Like millions from many nations before them, these migrants are being pushed out of their homes by one set of drivers and are being pulled to a destination by others. The frightful conditions in Honduras, Guatemala and El Salvador provide the push. The pull is family reunification with adult relatives who are already in the United States.

No policy response will stem the crisis let alone resolve the underlying phenomenon without addressing both parts of the equation.

The children's exodus burst into the news and the policy agenda this summer because of the now-familiar statistics on the surging number of apprehensions. What's gone largely unnoticed is a steady and substantial increase in the number of adults coming to the U.S. from Central America since the end of the Great Recession.

There are no exact counts on how many immigrants come to live in the U.S., and so we have to piece a picture together from various surveys and estimates. I did some fiddling with several different kinds of numbers and the results all point in the same direction.

The number of Central American immigrants living in the U.S. increased by nearly a quarter of a million between 2009 and 2012, according to the Census Bureau's American Community Survey. That is an eight percent bump in three years when overall migration was flat, reflecting the job market. The number of Mexican migrants increased by only one percent during the same three years.

So who were these folks?

Men looking for work so they could send money home to their families.

That's what the data tells us.

There is a funny population statistic called the "sex ratio" that can be very revealing in these circumstances. It is the number of men per every 100 women in a given population group. A normal sex ratio is about 95 because women live longer than men. The American Community Survey in 2012 (the last year available) tell us that for the whole foreign born population the sex ratio is 96 men for every 100 women, basically normal. Among Asian immigrants who entered the country since 2000, it was 85. That is a migration flow that tilts towards women. For Mexicans it was 118, that is a lot of men traveling alone. For Central Americans it was whopping 136 men for every 100 women. That is off the charts. Human adults simply do not form societies in which there are so many more men than women unless it is for a very specific purpose like waging war or, in this case, making money.

You can follow the money through remittance transfers, dollars sent by immigrants to families back home. Remittance flows from the U.S. to Latin America dropped sharply during the recession, and in the case of Mexico the numbers are still not back to pre-recession levels. But, remittance flows to Central America have not only recovered, they are booming.

The Inter-American Development Bank reports that in 2013 alone remittances to Central America were up by 5.4 percent, marking four years in a row of similar gains, and putting the growth rate for these countries ahead of any other region in Latin American and the Caribbean.

Super-high sex ratios and rapidly increasing remittance flows are sure signs of a classic, male-dominated labor migration. It has happened many times and in many parts of the world. And, not surprisingly, when you see that kind of a migration it is just a matter of time until the women and children follow. Indeed, you can figure that some of that big increase in remittances, a 7.8 percent bump for Honduras alone in 2013, is money that is financing trips north.

Every child living in a slum in a place that can be called the "murder capital" of anything has equal reason to want to leave. But they don't all leave and not all the ones that leave end up on the Rio Grande. The ones that cross the river have an additional reason for coming to the U.S. Their families are already here.

According to estimates cited by the Migration Policy Institute, 85 percent or more of the children apprehended at the border are being placed with a parent or close relative somewhere in the U.S.

President Obama and Congressional Republicans can out do each other with macho boasts about how the kids are going to get sent back to Central America. But, that talk will get hollow and ugly when they confront the fact that the grown ups are here. No U.S. government is going to take children away from their parents and deporting whole families will make this a much bigger, more difficult and more costly exercise, both financially and politically.

Managing a crisis is a lot harder when all your basic policies are broken, and maybe the only point of unanimous agreement about immigration is that the status quo is very badly broken.

But, since no one is going to fix it, we are just going to keep discovering crazy ways that policy failure comes back to bite us.