America's demography in the new century will be affected by the aging baby boom generation and by new immigrants. Focus on just the national implications of aging baby boomers and the new immigrants is inadequate. This policy brief takes a regional perspective, examining recent trends and population statistics and making the case that aging baby boomers and new immigrants are creating regional demographic divisions that will be just as important as old distinctions such as city versus suburb or rural versus urban. The new demographic divisions will encompass entire metropolitan areas and states, distinguishing between melting pot regions and heartland regions. Section 1 of the report presents an "Introduction." Section 2, "Reaching the 'Tail of the Python'," focuses on "The'Yuppie Elderly' among Today's Retirees"; "New Metro Growth Areas for Seniors"; and "When Boomers Become Seniors." Section 3, "Immigration and 'Multiple Melting Pots'," discusses "Immigrant and Domestic Migrant Magnets"; "Growing Ethnic Markets"; "Melting-Pot Metros"; and "California and the Rest of the West." Section 4, "Economic, Marketing and Political Implications," discusses "Baby Boomers as Retirees"; "Hispanics as Consumers"; and "Asian Consumers Emerge." Section 5 presents "New Regional Demographics." (Contains 39 references.) (SM)