Projected population by generationMillennials have surpassed Baby Boomers as the nation’s largest living adult generation, according to population estimates from the U.S. Census Bureau. As of July 1, 2019 (the latest date for which population estimates are available), Millennials, whom we define as ages 23 to 38 in 2019, numbered 72.1 million, and Boomers (ages 55 to 73) numbered 71.6 million. Generation X (ages 39 to 54) numbered 65.2 million and is projected to pass the Boomers in population by 2028.

The Millennial generation continues to grow as young immigrants expand its ranks. Boomers – whose generation was defined by the boom in U.S. births following World War II – are aging and their numbers shrinking in size The generations definedas the number of deaths among them exceeds the number of older immigrants arriving in the country.

Because generations are analytical constructs, it takes time for popular and expert consensus to develop as to the precise boundaries that demarcate one generation from another. In early 2018, Pew Research Center assessed demographic, labor market, attitudinal and behavioral measures to establish an endpoint – albeit inexact – for the Millennial generation. Under this updated definition, the youngest “Millennial” was born in 1996.

Here’s a look at some generational projections.

How we did this

Millennials

  • With immigration adding more numbers to this group than any other, the Millennial population is projected to peak in 2033, at 74.9 million. Thereafter, the oldest Millennial will be at least 52 years of age and mortality is projected to outweigh net immigration. By 2050 there will be a projected 72.2 million Millennials.
Births underlying each generation

Generation X

  • For a few more years, Gen Xers are projected to remain the “middle child” of generations – caught between two larger generations, the Millennials and the Boomers. Gen Xers were born during a period when Americans were having fewer children than in later decades. When Gen Xers were born, births averaged around 3.4 million per year, compared with the 3.9 million annual rate from 1981 to 1996 when the Millennials were born.
  • Gen Xers are projected to outnumber Boomers in 2028, when there will be 63.9 million Gen Xers and 62.9 million Boomers. The Census Bureau estimates that the Gen X population peaked at 65.6 million in 2015.

Baby Boomers

  • Baby Boomers have always had an outsize presence compared with other generations. They peaked at 78.8 million in 1999 and remained the largest living adult generation until 2019.
  • By midcentury, the Boomer population is projected to dwindle to 16.2 million.

Note: This is an update of a post originally published on Jan. 16, 2015. See the “How we did this” box for details.