America is swiftly becoming a granny state.

Less frail and more involved, today’s grandparents are shunning retirement homes and stepping in more than ever to raise grandchildren while young adults struggle in the poor economy.

The newer grandparents are mainly baby boomers who are still working, with greater disposable income. Now making up 1 in 4 adults, grandparents are growing at twice the rate of the overall population and sticking close to family — if their grandkids aren’t already living with them.

Grandparents in recent decades have often filled in for absent parents who were ill or battled addiction, or were sent to prison. The latest trend of grandparent involvement, reflected in census figures released Thursday, is now being driven also by the economy and the graying U.S. population, including the 78 million boomers born between 1946 and 1964 who began turning 65 this year.

“Grandparents have become the family safety net, and I don’t see that changing any time soon,” said Amy Goyer, a family expert at AARP. “While they will continue to enjoy their traditional roles, including spending on gifts for grandchildren, I see them increasingly paying for the extras that parents are struggling to keep up with — sports, camps, tutoring or other educational needs, such as music lessons.”

The latest numbers are based partly on separate analyses by Goyer and Peter Francese, founder of American Demographics magazine who is now a population analyst for the MetLife Mature Market Institute. Their data were supplemented with the latest 2010 census figures as well as interviews with Census Bureau and other experts.

In all, there are 62.8 million grandparents in the U.S., the most ever. They are projected to make up roughly 1 in 3 adults by 2020.