LOS ANGELES (CBS) — Tougher times and healthier lifestyles are just a couple of factors behind an increase in the number of Americans living well into their “golden years”, a USC professor said Thursday.

KNX 1070′s Bob Brill reports the U.S. Census Bureau says more people are living to 90 years old than ever before.

“Most people who actually make it to old age will live to be close to 90 at least,” said USC professor of gerontology Dr. Ilene Crimmins.

Nearly two million Americans are 90 years of age or more, according to government figures.

The reason more folks are living longer has always been traditionally linked to improved health and eating habits and eliminating or reducing harmful lifestyle habits like smoking and drinking alcohol.

But with longer lives comes the need for livelihoods to last longer — a reality underscored by data showing survivors over the age of 90 are more likely to live in poverty than the 65-89 demographic.

Dr. Crimmins points to a past event that may have prepared seniors for even more adversity: the Great Depression.

“Because they’re actually survivors of their earlier life, they survived in much greater numbers to be 90,” she said.

While the Census Bureau warns longer lifespans will ultimately strain the U.S. health care system, Dr. Crimmins said enhanced treatments may serve to negate that impact.