TUCSON, AZ: “Who are You?” That’s the question CBP agents worry about millions of times every day when people cross U.S. borders. During my visit to the port of entry in Nogales, Arizona—I learned about better ways to get that question asked and answered.

Knowing who you are is a critical element of border security—because if Customs and Border Protection, or CBP (part of the Department of Homeland Security) knows who you are they can pretty much tell if you are legally entitled to enter to U.S. It also helps them find bad people. On average, at the Nogales port of entry every week they will arrest one to dozen criminal aliens (people with felony records). On average, up to a half dozen of them will be sexual predators.

At the crossing station in Nogales, CBP agents showed the biggest part of the problem—a table with hundreds of documents that in the past had been authorized as proof of U.S. citizenship or other documentation to enter the U.S. from Mexico—many of them were fraudulent documents at that. Adequately inspecting this deluge of documents at the border was simply mission impossible.

The Department of Homeland Security came with a simple and effective answer—reduce the number of documents that serve as proof of US citizenship to three—a passport, a State Department issued border crossing card, or a state driver’s license that meets national standards (as set by the REAL ID Act). Implementing this requirement simply makes great sense.