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New research narrows the finding even further.
According to data analysis from Torsten Sløk, an economist at Deutsche Bank Securities, there are more 26-year-olds in America than any other age group - 4.75 million of them to be precise.
Sløk's analysis found these so-called "echo boomers" are poised to wield a great deal of influence in the coming years.
Just as Baby Boomers took over business, politics, and the consumer economy during the 1980s and '90s, millennials currently in their mid-twenties will come to make up the majority of jobs and big-ticket purchases, such as houses and cars, Sløk wrote in a recent report acquired by Axios.
In other words, their behavior will "echo" those of their parents.
Sløk's findings go against much of the research into millennial spending behavior. Increasingly, young people are moving into cities to rent, not buy, and many prefer to spend their money on experiences over material goods. Saddled with extraordinary college debt, some millennials feel they don't yet have the means to replicate their parents' behavior just yet.
But there's another way to read Sløk's findings, which is that millennials will represent such a large chunk of the spending economy - there are 83 million of them, after all - that what they spend money on won't matter as much.
Millennials may echo their parents' behavior in stimulating the economy through spending, but instead of new cars and houses, the hallmarks could become ride-sharing and a desire to travel the world.