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

The image and the costs of a Berlin-like wall or a Great Wall of China is something that the American people have not accepted to date.

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.

The potential of Mexico, Canada and the United States is enormous. We have a combined population of half a billion people; peaceful trade-friendly borders that are the envy of the world; the prospect of energy independence is within reach and will change the geopolitical situation of United States; we do a trillion dollars in trade among the three countries; more than 18,000 American companies are involved in foreign direct investment in Mexico and Canada; an increasing number of Mexican companies are creating jobs in the United States.

In the last two years, the Mexicans have detained nearly 400,000 migrants whose intent was to come to the United States. The Mexicans return the detained Central American migrants by bus or by air to the countries they come from.

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.

We must recognize that this massive economic bloc that's emerging in North America cannot be accomplished unilaterally. It must be accomplished in partnership with Mexico and Canada. And we have to work together to secure the continent in order to keep dangerous people and dangerous things out and strengthen perimeter security on a continental basis.