America should be working more with the Mexicans to prevent the flow of guns going south into Mexico that have fueled so much of the violence there, and the smuggling of cash and the money laundering that transnational criminal organizations have instituted in North America, including in the United States.

People in our so-called Rust Belt have lost out, and politics and society have not been responsive either in providing the kind of additional support they need or to retrain them for jobs that are being created in the new economy.

Migrants come up and no longer seek to evade the Border Patrol, but are actually left at the border by their smugglers. And they seek out Border Patrol agents or Customs and Border Protection officials to surrender to them and request political asylum. That's the way in which they get entry into a system that will eventually release them into the country.

The work the Mexicans are doing in terms of migration control on Mexico's southern border is crucial to our own border security.

If you build a 50-foot wall, you'll soon be confronted with a 51-foot ladder.

We can't defend the country by looking at the borderline as the first line of defense rather than as the last line of defense. We have to secure the flow of goods and people by engaging with foreign entities. We assure our security by securing the flows as early as we can before they arrive and as far away from our borders as we can.

The Mexican people are increasingly middle class, and Mexico has substantially become a middle-class society. This is true despite the significant poverty, and the class and geographic inequality that have deep historical roots.