For the first time since 1947, America's most common age is no longer part of the Baby Boom generation. Millennials have taken over.

According to Census Bureau information, 22-year-olds are the most represented age group in America, followed by 23-year-olds and then 21-year-olds. In fourth place comes 53-year-olds — those born at the tail end of the Baby Boom, 1961— who are the most-represented Baby Boomer age cohort. The shift occurred either in 2011 or late 2013, the Census estimates. Baby Boom is officially defined by the Census as those born between 1946 and 1964.

The rising prevalence of young 20-somethings can be explained by a combination of immigration and aging. Immigration has added people to the ranks of ages up until about 40 years old, when it begins to tail off. That means that the younger age groups continue to grow in size as the older ones start to fade away.

It's also worth noting that another name for Millennials is the "Echo Boom," the kids of those who themselves were part of the original Baby Boom. The years 1991-93 were particularly good for baby-making, it seems.