There is no doubt that the approximately 78 million Baby Boomers, born between 1946 and 1965, still represent the 800-pound gorilla of demographic market segments. Now in middle age and in their prime earning years, Baby Boomers' economic clout is reaching its peak and, as in the past, the group continues to shatter the precedents set by earlier age groups: Boomers reinvent the lifestyles, consumer patterns and location preferences of each new life stage they enter. However, the smaller Post-Boomer/Young Adult cohort of approximately 59 million, born between 1966 and 1980, is beginning to flex its muscles. New Census 2000 data shows another distinction: an increasing divide in geographic distribution patterns between these 2 generations.