Joe Vier was on track for a secure retirement as an advertising executive in the Detroit auto industry. He was making more than $100,000 a year and contributing to his 401(k) savings plan at work. That was in 2008. Then the S&P 500 tumbled roughly 50 percent and $2.7 trillion in retirement accounts were lost in the crash. Detroit was particularly hard hit — bankruptcies in the auto industry led to mass layoffs and a foreclosure crisis that brought the city to its knees.

The city of Detroit has faced serious economic challenges in the past decade, with a shrinking population and tax base while trying to maintain essential services. Getty Images

A decade later, Vier, 58, is working at a Florida theme park as a photographer. He said he was never able to find another position in his field. "I had worked my whole career in automotive advertising, it kind of pigeonholed me," Vier said. His annual income now is about $25,000, which makes it difficult to save for retirement. "I'm contributing a little bit but nothing like when I was in advertising and it's impossible to build a nest egg back up," he said. In a survey of workers from the Transamerica Center for Retirement Studies, 56 percent of respondents said they have not fully recovered from the Great Recession. Of those respondents, 37 percent said they have somewhat recovered, 12 percent said they have not begun to recover and 7 percent said they may never recover.