Zinke said his trip would help him mitigate environmental concerns in sensitive areas managed by Interior.
Interior manages nearly 177 miles of Arizona's border with Mexico, a stretch that crosses national monuments, tribal lands, and wildlife refuges that fall under Zinke's jurisdiction. Interior-managed lands touch about 39 percent of the entire U.S.-Mexico border.
"Clearly, we're going to build a wall," he told reporters while standing feet from the international boundary. "Clearly, the design is not yet finished."
Zinke's tour of the border was his first as Interior secretary. He will spend four days in Arizona to discuss border security as well as the opioid crisis.