The United States and Mexico share vitally important security, energy, and economic interests that require extensive cooperation and trust to achieve success. As Mexico’s president-elect Andres Manuel Lopez Obrador prepares to take office in December, I believe the next chapter in U.S.-Mexico relations will be critical to building on current efforts and increasing positive results for both Americans and Mexicans alike.Our two countries have a long history as neighbors, and we are deeply integrated on many critical security priorities. Violence in Mexico affects U.S. border towns, growing amounts of fentanyl . . .