Four senators, Democrats Mark Udall and Tom Harkin and Republicans Tom Coburn and John McCain, last month said they plan to introduce legislation dubbed the Currency Optimization, Innovation and National Savings, or COINS, Act.

The federal government has twice tried to coerce Americans into carrying more pocket change to no avail. The U.S. Mint began issuing the Susan B. Anthony $1 coins in 1979 but subsequently stopped production in 1999. In 2000, the Mint began producing $1 Sacagawea coins but those never truly caught on.

A coalition of cash-intensive business groups including small businesses and mass transit agencies has come out in favor of the conversion but other business groups argue the conversion would be costly and time consuming.

Eventually, all vending machines, coin-ops, cash registers and overnight bank deposit drops would have to be modified to accept the coins en masse. Businesses that ferry large amounts of hard currency would incur higher transportation and labor costs as a result.

Not to mention consumers, the largest interest group in the equation, would have to make some extra pocket space.

Advocates note First World countries that have made the conversion did so by slowly removing low denomination paper bills from circulation -- and public opposition diminished over the time period eventually resulting in widespread acceptance.