At this rate, the United States is going to need immigrants of all kinds to continue growth.

A new Census Bureau study has just reported a sobering commentary on the current generation of young people.

“There are now more young people living with their parents than in any other arrangement…What is more, almost 9 in 10 young people who were living in their parents’ home a year ago are still living there today, making it the most stable living arrangement.”

It’s a factor largely of the economy, but also social mores and trends. The traditional lifetime pattern, you may recall, was for young people to leave their parents’ home for college or shortly after. After graduation, they got a job, set up their own accommodation and the usual courtship routine began. All this in their 20s.

Now, the Census reports, that process has largely been pushed into the 30s. Most still marry, but later, reducing the window for children in families.

But today the primary living arrangement between the ages of 18 and 34 is to live, spouseless, back in their parents’ home. That’s almost 23 million Americans, three million more than residing with a spouse.

And this has all happened rather quickly, as demographic changes go. As late as 2005, a majority of these young people lived independently in their own household, the dominant living arrangement in 35 states. Ten years later that was the case in only six states.

The states with the highest percentage of re-filled empty nests are concentrated on the coasts, while states with the lower percentages are in Mountain and Midwestern states.

Of those living with Mom and Dad, one-in-four is unemployed or not attending school. This mirrors a decline in the economic status of young men. In 1975, Census points out, only 25% of males between 25 and 34 earned less than $30,000 a year. Last year that percentage was a whopping 41%.

All of which is ominous economically in part because of the student debt situation. Not only have those with college loans grown from 17% in 1989 to 41% in 2013, but the size of the debts has nearly tripled.

Young people are still marrying at roughly the same rate, but older. Surveys show the ideal age most Americans consider for marriage is 25 with the young people graduated and supporting themselves. But today only 24% are married by then.

About 20 years ago women had a 59% chance of marriage by age 25. By 2010, that was down to 44%. Yet the percentage actually married by age 40 changed little, from 86% to 84%. All of this can delay having children, and reduce the number likely.

However, the Census study also revealed a stunning statistic that usually presages poverty: “Parenthood now precedes marriage for many women. Nearly 40% of all births in the United States are to unmarried women.”