Montana is a state in the Western region of the United States. The state's name is derived from the Spanish word montaña (mountain). Montana has several nicknames including "Big Sky Country" and "The Treasure State", and slogans that include "Land of the Shining Mountains" and more recently "The Last Best Place". Montana is ranked 4th in size, but 44th in population and 48th in population density of the 50 United States. Montana is referred to as the "Treasure State" because of its rich mineral reserves. Mining has been an economic cornerstone of the state and the state's motto "Oro y Plata," Spanish for gold and silver, refers to two of the minerals that gave rise to the nickname.