 Indeed, the state capital of Yucatán, Mérida, is farther north than Mexico City or Guadalajara.Beginning approximately from the United States border, the Sierra Madre Occidental mountain range extends about south to the Río Santiago, where it merges with the Cordillera Neovolcánica range that runs east-west across central Mexico.The Sierra Madre Occidental lies approximately inland from the west coast of Mexico at its northern end but approaches to within fifty kilometers of the coast near the Cordillera Neovolcánica.