This article from 2000: https://lmtribune.com/nation/world/u-s-population-to-double-by-minorities-older-people-will/article_cc7371fa-988d-5900-b7a8-490abee9ff43.html said in 2011, we will have 300 million. In 2007, we actually reached such a number (https://www.populationpyramid.net/united-states-of-america/2007/) It expects the population to reach 400 million in 2050, and 500 million in 2100. In 2021, the U.S. population is one-third of a billion. 2020, 330 million. If we grow 21 million people per decade (which is easy to accomplish), we can easily see 500 million people, by growing 2 million people a year, which we currently are at. Abortion can be stopped; immigration could be relaxed; drugs could be illegalized; health and life expectancy could be well over 90 years by then, and the US will have 500,000,000 people in 2100 and continue growing, possibly aiming to be the most populous country, as Nigeria will slow down, as Congo will try and fail to reach the U.S., as China and India decline, and as Europe slows down its decline and starts rising.
The United States's population will surely reach 500 million by 2100