The United States has several coins and banknotes which were proposed at one time but never adopted.
A three dollar bill was proposed two times during the 1860s. A design was engraved for a potential $3 United States Note, and a 1865 law called for a $3 National Bank Note, but neither proposal came to fruition.
|$3 note||Not to be confused with fake or privately issued obsolete notes or the three-dollar Continental currency banknotes issued during the American Revolution|
There have been several United States coins which were proposed but never adopted. Most of the coins listed below, although never adopted, were produced in limited numbers as patterns.
| Silver center cent |
|4.48 g||24.00 mm||Cu (ring)|
|reeded||1792||The first and only US bi-metallic coin until the 2000 Library of Congress ten dollar coin.|
| Ring cent |
|various weights||90% Cu |
10% Ag α
|various||1850–1851, 1853 β , 1884–1885||196 ring cents (originals and restrikes) are known to exist.  Examples exist with or without a hole.|
| Aluminum cent |
|0.937 g||19.05 mm||96% Al |
4% trace metals
| Two-cent billon |
|3.84 g||~13.00 mm||90% Cu|
|Two and a half cent piece|
|unknown||unknown||unknown||unknown||never minted||Proposed in 1916 by US mint director Robert W. Woolley.  |
Civil War tokens of this denomination exist.
| Three-cent bronze |
|10.89 g||28.57 mm||95% Cu|
| Ring nickel |
|Gold ring half dollar|
|Gold ring dollar|
|1849, 1852|| |
|Two dollar piece|
|unknown||unknown||unknown||unknown||never minted||Proposed but not minted.  Some privately struck renditions exist. |
| Stella |
|7.00 g||22 mm||6.00g Au|
| Half-union |
|83.58 g||50.80 mm||90% Au|
10% Cu γ
|reeded||1877|| Commemorative coins of this denomination were issued in 1915. |
Several bullion coins are produced in this denomination.
| Union |
|unknown||never minted||Canceled before any patterns could be minted (fantasy coin shown). |
Some commemorative and bullion coins are minted in this denomination.
The cent, the United States one-cent coin, often called the "penny", is a unit of currency equaling one one-hundredth of a United States dollar. It has been the lowest face-value physical unit of U.S. currency since the abolition of the half-cent in 1857. The first U.S. cent was produced in 1787, and the cent has been issued primarily as a copper or copper-plated coin throughout its history.
1943 steel cents are U.S. one-cent coins that were struck in steel due to wartime shortages of copper. The Philadelphia, Denver, and San Francisco mints each produced these 1943 Lincoln cents. The unique composition of the coin has led to various nicknames, such as wartime cent, steel war penny, zinc cent and steelie. The 1943 steel cent features the same Victor David Brenner design for the Lincoln cent which had been in use since 1909.
A double eagle is a gold coin of the United States with a denomination of $20. The coins are 34 mm x 2 mm and are made from a 90% gold and 10% copper alloy and have a total weight of 1.0750 troy ounces.
The Liberty Head nickel, sometimes referred to as the V nickel because of its reverse design, is an American five-cent piece. It was struck for circulation from 1883 until 1912, with at least five pieces being surreptitiously struck dated 1913. The obverse features a left-facing image of the goddess of Liberty.
The half dime, or half disme, was a silver coin, valued at five cents, formerly minted in the United States.
A pattern coin is a coin which has not been approved for release, but produced to evaluate a proposed coin design. They are often off-metal strike, to proof standard or piedforts. Many coin collectors collect and study pattern coins because of their historical importance. Many of the world's most valuable coins are pattern coins; nearly 25 of the pieces listed in 100 Greatest US Coins are pattern coins.
The Indian Head cent, also known as an Indian Head penny, was a one-cent coin ($0.01) produced by the United States Bureau of the Mint from 1859 to 1909. It was designed by James Barton Longacre, the Chief Engraver at the Philadelphia Mint.
The United States large cent was a coin with a face value of 1/100 of a United States dollar. Its nominal diameter was 11⁄8 inch (28.57 mm). The first official mintage of the large cent was in 1793, and its production continued until 1857, when it was officially replaced by the modern-size one-cent coin.
The Flying Eagle cent is a one-cent piece struck by the Mint of the United States as a pattern coin in 1856 and for circulation in 1857 and 1858. The coin was designed by Mint Chief Engraver James B. Longacre, with the eagle in flight based on the work of Longacre's predecessor, Christian Gobrecht.
The gold dollar or gold one-dollar piece is a gold coin that was struck as a regular issue by the United States Bureau of the Mint from 1849 to 1889. The coin had three types over its lifetime, all designed by Mint Chief Engraver James B. Longacre. The Type 1 issue has the smallest diameter of any United States coin minted to date.
The 1974 aluminum cent was a one-cent coin proposed by the United States Mint in 1973. It was composed of an alloy of aluminum and trace metals, and intended to replace the predominantly copper–zinc cent due to the rising costs of coin production in the traditional bronze alloy. Of the 1,571,167 coins struck in anticipation of release, none were released into circulation. To encourage congressional support for the new alloy, the Mint distributed several examples to US Congressmen. When the proposed aluminum cent was rejected, the Mint recalled and destroyed those coins. However, despite the recall, a few aluminum cents were not returned to the Mint, and those coins may remain at large. One example was donated to the Smithsonian Institution, while another was alleged to have been found by Albert P. Toven, a US Capitol Police Officer. A 1974-D specimen was found in January 2014 by Randall Lawrence, who said it was a retirement gift to his father, Harry Edmond Lawrence, who was Deputy Superintendent at the Denver Mint. Randall planned on selling it in a public auction, but the Mint demanded its return, saying that the coin was never authorized for release and therefore remains U.S. Government property. Lawrence ultimately surrendered the coin when the Mint showed that the aluminum cent had never been authorized to be struck in Denver, and there was no evidence that the coin had been a gift of any kind.
The half union was a United States pattern coin with a face value of fifty U.S. Dollars. It is often thought of as one of the most significant and well-known patterns in the history of the U.S. Mint. The basic design, featuring Liberty on the obverse, was slightly modified from the similar $20 "Liberty Head" Double Eagle, which was designed by James B. Longacre and minted from 1849 to 1907.
The Coronet large cent was a type of large cent issued by the United States Mint at the Philadelphia Mint from 1816 until 1839.
James Barton Longacre was an American portraitist and engraver, and the fourth Chief Engraver of the United States Mint from 1844 until his death. Longacre is best known for designing the Indian Head cent, which entered commerce in 1859, and for the designs of the Shield nickel, Flying Eagle cent and other coins of the mid-19th century.
The three-cent silver, also known as the three-cent piece in silver or trime, was struck by the Mint of the United States for circulation from 1851 to 1872, and as a proof coin in 1873. Designed by the Mint's chief engraver, James B. Longacre, it circulated well while other silver coinage was being hoarded and melted, but once that problem was addressed, became less used. It was abolished by Congress with the Coinage Act of 1873.
The two-cent billon was a pattern US coin struck in 1836 and initially proposed as part of the Act of January 13, 1837. Versions exist with either a reeded edge and coin orientation or a plain edge and medal orientation; however, those with the former tend to be original strikes, whereas the latter are always proof restrikes.
The ring cent or holey cent was a one-cent pattern coin first struck in various compositions and designs between 1850 and 1851 as part of an experiment on producing a cent with a reduced weight and diameter, as the rising price of copper had caused cents to cost more than their face value to produce. Many varieties exist, with differing designs as well as differing compositions, including billon (standard), aluminum, copper, cupronickel, nickel silver, nickel, silver, and white metal.
The 1942 experimental cents were pattern coins struck by the United States Mint to test alternative compositions for the penny.
The 2000 Sacagawea dollar – Washington quarter mule is an error coin featuring the obverse of a Washington quarter and the reverse of a Sacagawea dollar struck on a gold-colored dollar coin planchet. It is one of the first known authentic mule coins to be released into circulation by the United States Mint.
The Washington nickel is a pattern coin that was struck by the United States Mint in 1866 and again in 1909 and 1910.