The population is highly urbanized, with 82.3% of the population residing in cities and suburbs. Large urban clusters are spread throughout the eastern half of the United States (particularly the Great Lakes area, northeast, east, and southeast) and the western tier states; mountainous areas, principally the Rocky Mountains and Appalachian chain, deserts in the southwest, the dense boreal forests in the extreme north, and the central prairie states are less densely populated; Alaska's population is concentrated along its southern coast – with particular emphasis on the city of Anchorage – and Hawaii's is centered on the island of Oahu. California and Texas are the most populous states, as the mean center of U.S. population has consistently shifted westward and southward. New York City is the most populous city in the United States and has been since at least 1790.