United States dollar

United States dollar

Federal Reserve Notes (obverse)
ISO 4217
Code	USD (numeric: 840)
Subunit	0.01
Unit
Symbol	$, US$, U$‎
Nickname	show List
Denominations
Superunit
10	Eagle
100	Union (Proposed, never issued)
Subunit
1⁄10	Dime
1⁄100	Cent
1⁄1000	Mill
Symbol
Cent	¢
Mill	₥
Banknotes
Freq. used	$1, $5, $10, $20, $50, $100
Rarely used	$2 (still printed); $500, $1,000, $5,000, $10,000 (discontinued, but still legal tender); $100,000 (discontinued, not legal tender, and only used for specific purposes)
Coins
Freq. used	1¢, 5¢, 10¢, 25¢
Rarely used	50¢, $1 (still minted); 1⁄2¢, 2¢, 3¢, 20¢, $2.50, $3, $5, $10, $20 (discontinued, but still legal tender); $25, $50, $100 (not intended for circulation).
Demographics
Date of introduction	April 2, 1792; 232 years ago[1]
Replaced	Continental currency Various foreign currencies, including: Pound sterling Spanish dollar
User(s)	see § Formal users (19), § Informal users (8)
Issuance
Central bank	Federal Reserve
Website	federalreserve.gov
Printer	Bureau of Engraving and Printing
Website	bep.gov
Mint	United States Mint
Website	usmint.gov
Valuation
Inflation	2.8% or 2.5%
Source	BLS (February 2025) or BEA (January 2025)
Method	CPI or PCE
Pegged by	see § Pegged currencies

The United States dollar (symbol: $; currency code: USD; also abbreviated US$ to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official currency of the United States and several other countries. The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it into 100 cents, and authorized the minting of coins denominated in dollars and cents. U.S. banknotes are issued in the form of Federal Reserve Notes, popularly called greenbacks due to their predominantly green color.

The U.S. dollar was originally defined under a bimetallic standard of 371.25 grains (24.057 g) (0.7734375 troy ounces) fine silver or, from 1834,^[2] 23.22 grains (1.505 g) fine gold, or $20.67 per troy ounce. The Gold Standard Act of 1900 linked the dollar solely to gold. From 1934, its equivalence to gold was revised to $35 per troy ounce. In 1971 all links to gold were repealed.^[3] The U.S. dollar became an important international reserve currency after the First World War, and displaced the pound sterling as the world's primary reserve currency by the Bretton Woods Agreement towards the end of the Second World War. The dollar is the most widely used currency in international transactions,^[4] and a free-floating currency. It is also the official currency in several countries and the de facto currency in many others,^[5][6] with Federal Reserve Notes (and, in a few cases, U.S. coins) used in circulation.

The monetary policy of the United States is conducted by the Federal Reserve System, which acts as the nation's central bank. As of February 10, 2021, currency in circulation amounted to US$2.10 trillion, $2.05 trillion of which is in Federal Reserve Notes (the remaining $50 billion is in the form of coins and older-style United States Notes).^{[7][failed verification]} As of January 1, 2025, the Federal Reserve estimated that the total amount of currency in circulation was approximately US$2.37 trillion.^[8]

Article I, Section 8 of the U.S. Constitution provides that Congress has the power "to coin money".^[9] Laws implementing this power are currently codified in Title 31 of the U.S. Code, under Section 5112, which prescribes the forms in which the United States dollars should be issued.^[10] These coins are both designated in the section as legal tender in payment of debts.^[10] The Sacagawea dollar is one example of the copper alloy dollar, in contrast to the American Silver Eagle which is pure silver. Section 5112 also provides for the minting and issuance of other coins, which have values ranging from one cent (U.S. Penny) to 100 dollars.^[10] These other coins are more fully described in Coins of the United States dollar.

Article I, Section 9 of the Constitution provides that "a regular Statement and Account of the Receipts and Expenditures of all public Money shall be published from time to time",^[11] which is further specified by Section 331 of Title 31 of the U.S. Code.^[12] The sums of money reported in the "Statements" are currently expressed in U.S. dollars, thus the U.S. dollar may be described as the unit of account of the United States.^[13] "Dollar" is one of the first words of Section 9, in which the term refers to the Spanish milled dollar, or the coin worth eight Spanish reales.

In 1792, the U.S. Congress passed the Coinage Act, of which Section 9 authorized the production of various coins, including:^[14]: 248

Dollars or Units—each to be of the value of a Spanish milled dollar as the same is now current, and to contain three hundred and seventy-one grains and four sixteenth parts of a grain of pure, or four hundred and sixteen grains of standard silver.

Section 20 of the Act designates the United States dollar as the unit of currency of the United States:^{[14]: 250–1}

[T]he money of account of the United States shall be expressed in dollars, or units...and that all accounts in the public offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation.

Unlike the Spanish milled dollar, the Continental Congress and the Coinage Act prescribed a decimal system of units to go with the unit dollar, as follows:^[15][16] the mill, or one-thousandth of a dollar; the cent, or one-hundredth of a dollar; the dime, or one-tenth of a dollar; and the eagle, or ten dollars. The current relevance of these units:

• Only the cent (¢) is used as everyday division of the dollar.
• The dime is used solely as the name of the coin with the value of 10 cents.
• The mill (₥) is relatively unknown, but before the mid-20th century was familiarly used in matters of sales taxes, as well as gasoline prices, which are usually in the form of $ΧΧ.ΧΧ9 per gallon (e.g., $3.599, commonly written as $3.59+9⁄10).^[17][18]
• The eagle is also largely unknown to the general public.^[18] This term was used in the Coinage Act of 1792 for the denomination of ten dollars, and subsequently was used in naming gold coins.

The Spanish peso or dollar was historically divided into eight reales (colloquially, bits) – hence pieces of eight. Americans also learned counting in non-decimal bits of 12+1⁄2 cents before 1857 when Mexican bits were more frequently encountered than American cents; in fact this practice survived in New York Stock Exchange quotations until 2001.^[19][20]

In 1854, Secretary of the Treasury James Guthrie proposed creating $100, $50, and $25 gold coins, to be referred to as a union, half union, and quarter union, respectively,^[21] thus implying a denomination of 1 Union = $100. However, no such coins were ever struck, and only patterns for the $50 half union exist.

When currently issued in circulating form, denominations less than or equal to a dollar are emitted as U.S. coins, while denominations greater than or equal to a dollar are emitted as Federal Reserve Notes, disregarding these special cases:

• Gold coins issued for circulation until the 1930s, up to the value of $20 (known as the double eagle)
• Bullion or commemorative gold, silver, platinum, and palladium coins valued up to $100 as legal tender (though worth far more as bullion).
• Civil War paper currency issue in denominations below $1, i.e. fractional currency, sometimes pejoratively referred to as shinplasters.