California has emerged as the most populous state and one of the top 10 economies in the world. Massive late 19th–20th century population and settlement booms created two megalopolis areas of the Greater Los Angeles/Southern California and the San Francisco Bay Area/Northern California regions, one of the nation's largest metropolitan areas and in the top 25 largest urban areas in the world. Four more metropolitan areas of San Bernardino-Riverside, San Diego, Denver, Phoenix, and Seattle have over a million residents, while the three fastest growing metro areas were the Salt Lake City metropolitan area, the Las Vegas metropolitan area; and the Portland metropolitan area.