NEW YORK (CNN/Money) - The federal government will unveil a new $20 bill that will introduce a predominant but subtle color into the background, marking the first time in modern history that a U.S. bill will feature a color other than green.

The Bureau of Engraving hasn't said what color it will choose for the new $20, but think of the possibilities.

According to the Treasury Department, other changes will include new images of Andrew Jackson and the White House, as well as other adjustments that are being kept secret. The official unveiling will take place on March 27, with the new bill entering circulation in the fall.

The last redesign of American currency was in 1996, when a new $100 bill was introduced with new features to thwart counterfeiters. A new $50 came in 1997, followed by the $20 in 1998 and new $5 and $10 notes in 2000.

New features on those notes included new ink that appeared black from one angle and green from another; a watermark, visible only when holding the bill up to the light; and a security strip that ran vertically through the bill. While these features also will be included on the new redesigned bills, they may not fix the problem of counterfeiting.

The Secret Service says the percentage of counterfeit bills produced digitally produced has grown from 1 percent of counterfeit bills in 1995 -- before the last redesign -- to a whopping 40 percent in 2002.

Dennis Forgue, a rare currency dealer and anti-counterfeiting expert, said many international counterfeiters bleach the surface of small American bills and digitally print the face of a larger bill over them, even though the watermark and security strip remain the same.

"Unless there's some sort of penetrating ink, the new bills won't fix that problem," he said.

Since last summer, the Bureau of Engraving and Printing has been working with members of the vending machine, gaming and public-transit industries, whose operations could be affected by the new notes.

Brad Quay, vice president of Hamilton Manufacturing, said the department has been providing samples and working with his company, a maker of change machines and other currency handling products, based in Holland, Ohio.

The color in the new bills won't be a problem for the bill-acceptor machines his company makes, he said, but certain aspects of the bills' new appearance will require adjustments.