US Population by Age and Generation in 2020

Gen-Z has overtaken Millennials by nearly 4 million to become the largest generation in the United States. Baby Boomers are the third-largest generation with the population of 69 million persons in 2020.

With a current population of around 86 million, the Gen-Z generation is expected to grow to 88 million over the next 20 years because of migration, according to the United Nations' latest World Population Prospects.

The boundaries that define generations are not universally agreed, and yet these boundaries carry important implications in business and government. The size, financial security, and general health of each generation shapes everything from marketing campaigns to insurance and social welfare benefits to transportation and health services planning. 

• According to the Pew Research Center, the oldest Millenial was born in 1981 while the youngest was born in 1997.
• Synchrony Financial uses much lower boundaries, defining the Millenial generation as those born from 1976 through 1992.
• Considering still other definitions, the birth year of the oldest Millenial varies from 1976 to 1986 while the birth year of the youngest ranges from 1993 to 2010.