NEW YORK (MainStreet) — While most think of a bank when considering where to put savings, more and more of us apparently are thinking shoebox.

With many upbeat about the economy, more and more Americans are feeling optimistic about their future and putting a little aside for retirement or rainy days. However, a new survey from American Express shows 29% of Americans who are saving aren’t socking it way in banks, but rather will keep at least some of it in cash and coins — up from 25% last year. And of those keeping cash, 53% are hiding it in a secret location.

While American Express didn’t ask why people are keeping cash, the company's public affairs manager Kimberly Litt attributes the trend to increasing budget strategy.

“People use it as a budgeting technique, like keeping cash in envelopes set aside for a specific purpose and also keeping cash at home for emergencies.”

But is keeping cash a good practice?

“Hiding cash in a secret location is never a good idea,” said Coleen Pantalone, associate professor of finance at the School of Business at Northeastern University. “First, you might forget where you put it – we often put things in places that make sense at the time, but later, it's hard to remember. Second, if you don't tell anyone where it is and you suddenly die or become incapacitated, your heirs won't get the money.”

Pantalone said people who have lived through down economic times — like the Great Depression, or even the Great Recession — are more likely to keep cash on hand.

“The stock market crash in 2008 and ensuing deep recession left many Baby Boomers who were close to retirement shaken,” she added. “Keeping your savings in cash is a sign you distrust the system – often the result of the system failing you, à la stock market crashes.”

Kirk Chisholm, a financial advisor at Innovative Advisory Group in Lexington, Mass., added while the Great Recession never hit the lows of the 1930s, it likely shook people’s confidence in the strength of economic institutions.

“While 2008 did not end up taking (the Great Depression’s) path, it could have,” Chisholm said. “While many consumers consider cash to be somewhat of a barbaric form of money compared to credit or debit cards, there is a growing amount of consumers who are becoming more cautious about how they store their cash.

“There is a growing mistrust of the financial system,” he added.

People’s background also can affect their trust in banks and desire to keep money where they can see. Pantalone said folks with low incomes are less likely to use banks – since banks have minimum fee options that are not necessarily very welcoming to people with few assets. She added immigrants also are untrusting of banking institutions and the government, in general.

“They may have had negative experiences in their home country, and they are hampered by a new language and different laws and regulations,” Pantalone said.

While most agree it’s a good idea to store some cash in a safe place which is easily accessible, it’s equally important to remember the money you’re not making by holding onto your savings yourself.

“When banks pay a positive interest rate for holding your cash, there is an incentive for people to keep their funds there,” Chisholm said.

It’s also important to remember your assets — at least to a point — are protected by the FDIC when locked in a bank, said Michael Clark, a certified financial planner in Orland, Fla.

“If something bad happens the limits on insurance for cash [on hand] are low,” Clark said. “At least a bank has FDIC insurance that covers you if something happens with the bank.”

Clark adds that cash is not just insured in a bank but also has the potential to expand.

“Cash literally under your mattress does not allow it to grow,” he said. “Sure, [interest] rates are low, but some extra money is always better than none.”

--Written by Chris Metinko for MainStreet