On top of Social Security, workers need to contribute 9 percent of income, including any employer match, in a 401(k) to maintain their standard of living in retirement, Ghilarducci said. Many workers end up setting aside much less.
"We are human beings, and there is a bias for present consumption versus future consumption," Ghilarducci said.
This doesn't bode well for younger workers, who are more likely to have a 401(k) than a traditional pension.
Daral Johnson, a security guard in Baltimore, says he thinks about retirement.
"Time goes fast. It seems like a year or two ago I was 23, and now I'm 28," he said.
Even so, Johnson doesn't participate in his employer's 401(k). He said his wages are too low to contribute to the plan on top of all his other financial responsibilities. Johnson, the father of a 2-year-old son, earns $10.25 an hour and works about 35 hours a week.
"I'm barely getting by right now," he said.
Another flaw of the 401(k) is that it's too easy for workers to dip into the account, Ghilarducci said.
Johnson, for instance, participated in a 401(k) at a previous job but pulled money out to pay rent.
Ultimately, the lack of retirement savings won't be just a problem for workers, Ghilarducci said. Mayors and governors in the coming years will have to figure out how to meet the needs of a significant elderly population with little means, she said.
The Schwartz study found that Marylanders near retirement had an average household net worth, including home equity, of $282,325 for singles and $687,027 for married couples. That counts some very rich households pulling up the averages, the report said.
Exclude home equity, and 15 percent of these older households have less than $10,000 in savings, investments and retirement accounts, the report said.
That includes Baldassano. "I have zero for retirement," she said.
It wasn't always that way. She had a pension and a defined contribution plan years ago when working for a business publishing company. But she switched to part-time work to raise a son with special needs and later to care for ailing parents. When she divorced in 2007, she said, she drained her retirement funds to buy out her ex-husband's share of their Silver Spring house.
Baldassano said she earns up to $27,000 as an adjunct professor, if she teaches year-round. That's not enough to save for retirement, and it's hard for her to envision a time when she'll be able to stop working, she said.
"I would like to be able to look down the road and see a point at which I could do that," she said. "Right now, it's not there."