Mexico has become a robust democracy with a robust press and an active legislature. It has gone from being a sending country for migrants to a transit country, and increasingly a receiving country for migrants in its own right.

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

Homeland security is inherently transnational today. There's hardly anything adverse that happens in our homeland that doesn't have a cause or effect that's generated abroad. Increasingly, we must rely on our allies and foreign governments to share information and data to secure our country.

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.

We should be wary, particularly with our closest friends and allies, of breaking down the trust and confidence that lie at the foundation of relationships.

The idea was to restore the rule of law, to bring order to a chaotic situation. The results became more and more apparent. Crime rates went down in the border region. Today, the number of migrants crossing is at a 30-year low. That's because of years of bipartisan work on this issue.

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