The baby boomer generation, already bumped to second place in numbers by the millenial generation, looks soon to drop to third place behind "Generation Z,"reports.The boomer generation, which dominated America for decades until the middle of 2015, is set to be bumped down another spot through the rise of children who were born after the 21st century began and who grew up during the period following the 9/11 attacks.That segment, called "Generation Z" by some analysts, in the next few years is expected to overtake the baby boomer generation's second-place spot. Millenials represent people born in the 1980s and '90s.Baby boomers represent the huge numbers of births following the end of World War II, between 1946 and 1964, according to the U.S. Census Bureau, and their sheer numbers mean they dominated most of America's culture and politics for years. However, as the post-war generation became older, the number of millennials grew, and as of July 1, 2015, the most common age among Americans was 24, with 25-and 23-year-olds closely following.But the numbers of millennials and Generation Z people grew past the baby boomer generation because of more births and immigration, not by baby boomers dying off,.But baby boomers are expected to dominate the nation's wealth and spending for years to come. Also, voter turnout rises with age, so aging baby boomers will continue to be dominant in politics for decades more, the Journal notes.There are no official start and end dates for generations born in years other than the baby boomer decades, according to the Census Bureau, but the Pew Research Center considers those who were born before 1928 and young adults during World War II to be the "Greatest Generation."Meanwhile, the "Silent Generation" was born from 1928 to 1945 and were children during the Great Depression and World War II. "Generation X" came between 1965 and 1980, followed by millennials.