Since WWII, the state has been generally economically prosperous and enjoyed relatively high per capita income because of its location between major cities like Philadelphia, New York, and Washington, DC. Its population grew rapidly, particularly in the suburbs in the north where New Castle county became an extension of the Philadelphia metropolitan area. Americans, including migrants from Puerto Rico, and immigrants from Latin America flocked to the state. By 1990, only 50% of Delaware's population consisted of natives to the state.