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U.S. currency

Security features

The U.S. Treasury Department established the U.S. Secret Service in 1865 to curtail counterfeiting. However, protecting and maintaining confidence in U.S. currency requires a combination of effective law enforcement, public education, and security features. Starting in the 1990s, the U.S. government began redesigning Federal Reserve notes to stay ahead of counterfeiting threats. New features include watermarks, color-shifting inks, and security threads in the $5, $10, $20, $50, and $100 notes. These features make the notes easier to authenticate and more difficult to counterfeit.

The most recent series of redesigned notes began in 2003 with the new $20 bill. It was followed by the $50 note in 2004, the $10 note in 2006, and the $5 note in 2008. A new design for the $100 note, the last in the series, begins circulating in October 2013. No redesign is planned for the $2 and $1 notes.

Making Sense Of The Redesigned $100.00 Note

A new $100 note, the latest denomination of U.S. currency to have been redesigned, began circulating on October 8, 2013. The redesigned note features two new security features: the 3-D Security Ribbon and the "Bell in the Inkwell."

  • 3-D Security Ribbon: A blue ribbon is woven into the paper near the center of the note. The ribbon contains images of bells that change to 100s when you tilt the note. The bells and numbers move side to side when you tilt the note back and forth, and move up and down when you tilt the note side to side.
  • The Bell in the Inkwell: A copper inkwell containing a color-shifting bell is located to the right of the portrait. When you tilt the note, the bell changes from copper to green, making it seem to appear and disappear within the inkwell.

Like the other redesigned denominations, the $100 note features American symbols of freedom. Phrases from the Declaration of Independence and the quill the Founding Fathers used to sign the document are located to the right of the portrait on the front of the note. Like the previous $100 note, the redesigned note features a vignette of Independence Hall on the back, but it shows the rear of the building instead of the front. In addition, the vignette is larger and the oval that used to surround it has been removed.

The new $100 note retains several effective security and design features from the previous redesign in 1996: the portrait watermark of Benjamin Franklin, the security thread, and the color-shifting 100.

You can learn more about the redesigned $100 by visiting

You should know that you do not need to trade in your original notes for the new ones. All U.S. currency remains legal tender, regardless of when it was issued.

The slideshow below displays front and back images of the Federal Reserve notes in circulation.

Click on an image to explore currency.

The diagram below illustrates the security features of the redesigned $20 note, and is accompanied by a brief description.

  • Hover over the $20 bill to magnify its features. Use the tabs to navigate other security feature details.

  • A clear polyester thread, embedded vertically in the paper, has the denomination of the note inscribed on it. You can see the thread only when you hold it to the light. Each denomination has a unique thread position and glows a different color under an ultraviolet light. The security thread in the $20 note, for example, glows green when lit.

  • On the redesigned $10, $20, and $50 notes, the ink shifts from copper to green when you tilt the note. On the $100 note, this ink changes from green to black.

  • Microprinting is text so small that it is hard to replicate. Each denomination of redesigned U.S. currency includes microprinting in different areas of the note. On the $20 note, you can see it in two places. USA20 is printed in blue along the first three letters of the TWENTY USA ribbon to the right of the portrait, and THE UNITED STATES OF AMERICA 20 USA 20 appears in black along the border of the bill below the Treasurer's signature.

    The redesigned $5, $10, $20 and $50 notes also include subtle background colors, which differ for each denomination and make the notes more complex. Because potential counterfeiters can duplicate color, you should not rely on the color to verify the authenticity of the bill. Checking a combination of security features, such as the portrait watermark and security thread, is the most reliable way to verify authenticity.

  • A watermark is a faint image that is part of the paper itself. You can see the watermark from both sides if you hold the bill up to a light.

Other design features

Many physical characteristics of Federal Reserve notes have changed over time since the Federal Reserve first issued the notes in 1914, though the notes retain the traditional look and feel of U.S. currency. Many of the changes, including a smaller size and more standardized designs, first appeared in 1928 as part of the first set of sweeping changes to the currency.

Federal Reserve indicators

On redesigned notes, a seal representing the Federal Reserve System appears to the left of the portrait. A letter and number below the left serial number identify the issuing Federal Reserve Bank. (See chart.) The $1 and $2 notes, which have not been redesigned, feature the individual seal of the issuing Reserve Bank.

Hover over FRS map to view indicator symbols.

Symbols of freedom

The 2004 series of redesigned notes features different American symbols for each denomination. For example, two American eagles appear on the front of the $20 note. The large blue eagle in the background to the left of President Andrew Jackson's portrait represents the eagles drawn and sculpted during President Jackson's time. The smaller green metallic eagle to the lower right of the portrait is a relatively modern illustration, made with the same raised-ink intaglio process as the portrait, numerals, and engravings.


A new series year designation is necessary when the note's appearance undergoes a major change, when the signatures of the Secretary of the Treasury or the Treasurer change, or when there is a significant gap in production times.

Serial number

A unique combination of 11 numbers and letters appears twice on the front of each redesigned note. The first letter of the serial number corresponds to the series year (see chart).  The second prefix letter identifies the Federal Reserve Bank that issued the note. The $1 and $2 notes have only one prefix letter, which corresponds to the issuing Federal Reserve Bank. For example, the letter F, which represents the Sixth Federal Reserve District, would precede the serial number on a $1 note issued by the Federal Reserve Bank of Atlanta.


First prefix letter




$20, $50, $100



$5, $10, $20, $100



$5, $10, $20, $50, $100



$5, $10, $100



$5, $100



$20, $50



$10, $20, $50



$5, $100






$5, $10, $20, $50



$5, $10, $20, $50, $100






$5, $10, $20

Money Factory; U.S. Currency
Know Your Money

Because serial numbers are unique identifiers, they help law enforcement officials identify counterfeit notes. They also help the BEP track quality standards for the notes they produce.

Note on star notes: If the BEP detects an imperfect note during the manufacturing process after it has already overprinted the serial number, it replaces the flawed note with a new one, called a "star" note. However, to use the exact serial number would be costly and time-consuming, so the replacement note has its own special serial number followed by a star in place of a suffix letter—hence its name. The BEP does not reuse the serial number of the note that it replaced in the same numbering sequence.


Until July 1929, U.S. currency was 7.42 inches by 3.13 inches. Currency printed since then measures 6.14 inches by 2.61 inches, a size easier to handle and less expensive to produce.

Portraits and emblems

Federal Reserve notes feature portraits of American statesmen on the face and emblems and monuments on the back.

"In God We Trust"

Secretary of the Treasury Salmon P. Chase authorized the use of "In God We Trust" on U.S. money—on the 2¢ coin in 1864—after he received a number of requests from citizens. Several acts of Congress allowed for the motto to appear on all coins, although its use was not continuous for some time. In 1956, Congress declared "In God We Trust" the national motto and mandated the use of this phrase on all currency and coins.

The Great Seal of the United States

Although the Great Seal of the United States was created early in the history of the United States, the first currency note to include it in the design was the $1 silver certificate, series 1935. The seal has appeared on the reverse (green) side of all $1 notes since then.

Great Seal: Eagle

Great Seal: Eagle

In 1776, the Continental Congress appointed Benjamin Franklin, Thomas Jefferson, and John Adams to a committee to arrange for the preparation of a seal for the United States of America. This committee and two subsequent others labored over the design for six years. The third committee enlisted the aid of William Barton, the son of a Philadelphia Episcopal clergyman and an authority on heraldry. Barton created two designs, one of which Secretary of Congress Charles Thompson simplified. Congress adopted this simplified design in 1782. This design incorporates multiple sets of 13 items each, which represent the original 13 states.

The face of the seal, on the right-hand side of the bill, shows the American bald eagle with wings and talons outstretched. A "glory," or burst of light, containing 13 stars appears above the eagle's head. The right foot holds an olive branch with 13 leaves, representing peace; the left, a bundle of 13 arrows, symbolizing war. The eagle's head is turned toward the olive branch, indicating a desire for peace. The shield (with 13 stripes) covering the eagle's breast symbolizes a united nation. A ribbon in the eagle's beak bears the Latin motto E Pluribus Unum (13 letters), which means "out of many, one."

Pyramid: All Seeing Eye

Pyramid: All Seeing Eye

The back of the Great Seal, on the left side of the bill, depicts a pyramid, a symbol of material strength and endurance. The pyramid is unfinished, symbolizing a striving toward growth and a goal of perfection. Above the pyramid another glory contains an eye inside a triangle representing the eternal eye of God and placing the spiritual above the material. At the top edge is the 13-letter Latin motto Annuit Coeptis, meaning "He has favored our undertakings." The base of the pyramid bears the Roman numerals MDCCLXXVI (1776). Below this number is the motto Novus Ordo Seclorum, "a new order of the ages."