The City and County of San Francisco is the 4th most populous city in California and the14th-most populous in the US, with a 2006 estimated population of 744,041. San Francisco is the 2nd most densely populated major city in the U.S. It is a popular international tourist destination and characterized by a high standard of living. The great wealth and opportunity generated by the Internet revolution drew many highly educated and high income workers to San Francisco. Property values and household income have escalated to among the highest in the nation. Tourism is the backbone of the San Francisco economy.