We obsess over our generations the way we obsess over our horoscopes, recognizing that it's a dumb approximation of who we are but mining every description for the details that we think are correct. The advent of the clickbait Web has meant that we're awash with "You know you're a Millennial if" or "22 things only Gen Xers will remember" nonsense. And we mean "nonsense" in two ways: Those stories are usually fluff, and from a demographic perspective, the idea that Generation X is a set generation is nonsense.
The unofficial government arbiter of what is and isn't a generation is the Census Bureau. Its catalog of aggregated data on the lives of Americans recognizes only one official generation: The Baby Boomers. Howard Hogan, the bureau's chief demographer, explained why in an e-mail to the Post. "The Baby Boom is distinguished by a dramatic increase in birth rates following World War II and comprises one of the largest generations in U.S. history," Hogan wrote. "Unlike the baby boom generation, the birth years and characteristics for other generations are not as distinguishable and there are varying definitions used by the public." So the Census Bureau will put together numbers for Boomers, because that's a real, demographic generation. It doesn't release numbers on "Millennials" because you made that term up.
A quick survey of news reports on the different generations over time shows how generational indicators rise and fall. The chart below shows different proposed names from different time periods, spanning the length of each colored bar (or, when a start or end is nebulous, indicated in a lighter color). You think you're in Gen X, but 30 years ago, you'd have thought you were a Baby Buster. (Editor's note: I prefer Gen X.) You think that college kids are Millennials, but a decade ago some people might have called them "Nexters." (And little newborn baby reading this? The Times says you're Generation Z. I'll assume you probably do read the Times.)