The number of Americans ages 100 and older is projected to more than quadruple over the next three decades, from an estimated 101,000 in 2024 to about 422,000 in 2054, according to projections from the U.S. Census Bureau. Centenarians currently make up just 0.03% of the overall U.S. population, and they are expected to reach 0.1% in 2054.

…

The U.S. population overall is expected to trend older in the coming decades as life expectancies increase and the birth rate declines. There are currently roughly 62 million adults ages 65 and older living in the U.S., accounting for 18% of the population. By 2054, 84 million adults ages 65 and older will make up an estimated 23% of the population.

Even as the 65-and-older population continues to grow over the next 30 years, those in their 100s are projected to roughly double as a percentage of that age group, increasing from 0.2% of all older Americans in 2024 to 0.5% in 2054.