This post comes from Brian O'Connellat partner site MainStreet.

Americans are great at accruing loyalty rewards points, especially from retailers, banks and credit card companies. Unfortunately, they're just as good at not cashing those rewards in.

A new study from Colloquy, a marketing firm in Cincinnati, shows that about 33% of the 48 million rewards points earned by American consumers each year go unused, presumably due to neglect and misinformation, for a total value of $16 billion.

That news will probably make the companies that promote them happy, as the banks, credit card companies and retailers benefit from a huge de facto profit-making engine without having to lift a finger.

Of the $16 billion in unused loyalty points, the average American consumer squanders $205 -- enough to buy a round-trip plane ticket from Philadelphia to Miami, or to pay the average U.S. household phone bill for the month.

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"American consumers are leaving significant dollars on the table every year," says Kelly Hlavinka, a managing partner at Colloquy. "This report should alert savvy consumers to a great opportunity to stretch household budgets, and to do so by simply consolidating their loyalty rewards participation with their favorite brands, making it easy to accumulate and redeem them faster than ever imagined."

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Rules are hard to decipher

But one issue consumers have is trouble understanding what purchases do and don't qualify for the points. A cynic may wonder if complicated rewards rules are an intentional way for a company to make some extra cash, but it could be that either consumers are indifferent about using all their points (unlikely in this economy), or they're confused about how to leverage their rewards points, which the study's researchers feel is more likely. Post continues after video.

The study also reveals some interesting data on which industries are the most aggressive about offering rewards and travel miles. Not surprisingly, the financial sector tops that list:

• The financial services sector is the biggest provider of rewards at $18 billion a year.
• The travel and hospitality sector is the second-largest industry in terms of rewards at $17 billion a year.
• The retail industry, although it makes up 40% of all loyalty program memberships, issues the smallest value in rewards at $12 billion a year.

On the demand side, membership in such programs is up:

• The number of loyalty memberships in the U.S. is 2.1 billion, up from 1.8 billion in the 2009 report and exceeding 2 billion for the first time.
• The average household has signed up for 18.4 programs, compared with 14.1 programs in 2009.
• Despite the increase in overall membership, the average number of programs in which households actively participate is just 8.4.

It's up to rewards points providers to urge consumers to use their points, although that's not an alluring option when providers can save big bucks when shoppers don't use them. Plus, if you push a consumer too far, that business may never come back.

"If redemption equals engagement, and engagement delivers customer satisfaction and profits, then loyalty marketers should encourage their members to make the most of their rewards," Hlavinka said. "In short, redemption is good." (See MainStreet's rundown of the best credit card rewards.)

More on MainStreet and MSN Money:

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• Banks drop debit card rewards
• 6 reasons to keep using credit cards