The U.S. population is expected to peak in 2080 and shrink by the end of the century, according to a new Census Bureau estimate released Thursday.

It’s the first time the bureau has ever projected a population decline, a result of an aging population and declining birth rates.

The population is expected to peak at about 370 million people in 2080 and decline slightly to 366 million by the year 2100. The current U.S. population is about 332 million people.

“In an ever-changing world, understanding population dynamics is crucial for shaping policies and planning resources,” said Sandra Johnson, a demographer at the Census Bureau.

Previous Census projections, the most recent made in 2018, only extrapolated population until 2065. Thursday’s release is the first estimate to reach so far into the future.

Short-term factors, like the COVID-19 pandemic, played into the new estimate but also larger societal trends like people having fewer children.

“The U.S. has experienced notable shifts in the components of population change over the last five years,” Johnson explained. “Some of these, like the increases in mortality caused by the COVID-19 pandemic, are expected to be short-term while others, including the declines in fertility that have persisted for decades, are likely to continue into the future.” 

“Incorporating additional years of data on births, deaths and international migration into our projections process resulted in a slower pace of population growth through 2060 than was previously projected,” she continued.

Declining birth rates are a hallmark of modern developed countries. The trend is visible globally, with the most drastic example in Japan. That country’s birth rate fell to 1.26 this year, a record low. A rate of about 2.06 is considered to be needed to maintain a population.

The U.S. birth rate was 1.64 births per woman as of 2020, according to the Census. Immigration supplements that rate, leading to the country’s increasing population.

The Census projected that immigration will make up a larger portion of population growth over time, citing falling domestic birth rates. 

The population is also expected to age, which could create additional stresses on welfare systems that already face budget crunches. 

There are expected to be more people older than 65 years old than under 18 by 2029. Nearly 30 percent of Americans are projected to be over 65 in 2100, the Census said.