Complex sentence: Beginning in Utah, the corridor extends northward through western Wyoming and eastern Idaho to Yellowstone National Park and reaches south to San Bernardino, California on the west and through Mesa, Arizona on the east, extending to the U.S.-Mexico border.
Split into simpler sentences: Beginning in Utah, the corridor extends northward through western Wyoming and eastern Idaho to Yellowstone National Park. It reaches south to San Bernardino, California on the west and through Mesa, Arizona on the east, extending southward to the U.S.-Mexico border.