A wall has an obvious appeal. It represents a concrete and visible effort to keep immigrants out; it carries great symbolic power. But would it really keep immigrants from illegally entering the United States?

San Diego's Kevin Faulconer and Tijuana's Juan Manuel Gastelum didn't mention Trump or Peña Nieto by name at a joint news conference, but their concern about growing tension between the two countries and its potential economic impact was evident in their remarks