The state of Chihuahua is the largest state in the country and is known as El Estado Grande (The Big State); it accounts for 12.6% of the land of Mexico. The area is landlocked by the states of Sonora to the west, Sinaloa to the south-west, Durango to the south, and Coahuila to the east, and by the U.S. states of Texas to the northeast and New Mexico to the north. The state is made up of three geologic regions: Mountains, Plains-Valleys, and Desert, which occur in large bands from west to east. Because of the different geologic regions there are contrasting climates and ecosystems.