# United States dollar


By [Kara](https://paragraph.com/@kara-3) · 2024-01-17

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The **United States dollar** ([symbol](https://en.wikipedia.org/wiki/Currency_symbol): [**$**](https://en.wikipedia.org/wiki/Dollar_sign); [currency code](https://en.wikipedia.org/wiki/ISO_4217): **USD**; also abbreviated **US$** to distinguish it from [other dollar-denominated currencies](https://en.wikipedia.org/wiki/Dollar); referred to as the **dollar**, **U.S. dollar**, **American dollar**, or colloquially **buck**) is the official [currency](https://en.wikipedia.org/wiki/Currency) of the [United States](https://en.wikipedia.org/wiki/United_States) and [several other countries](https://en.wikipedia.org/wiki/International_use_of_the_U.S._dollar). The [Coinage Act of 1792](https://en.wikipedia.org/wiki/Coinage_Act_of_1792) introduced the U.S. dollar at par with the [Spanish silver dollar](https://en.wikipedia.org/wiki/Spanish_dollar), divided it into 100 [cents](https://en.wikipedia.org/wiki/Cent_\(currency\)), and authorized the minting of coins denominated in dollars and cents. U.S. banknotes are issued in the form of [Federal Reserve Notes](https://en.wikipedia.org/wiki/Federal_Reserve_Note), popularly called greenbacks due to their predominantly green color.

The [monetary policy of the United States](https://en.wikipedia.org/wiki/Monetary_policy_of_the_United_States) is conducted by the [Federal Reserve System](https://en.wikipedia.org/wiki/Federal_Reserve_System), which acts as the nation's [central bank](https://en.wikipedia.org/wiki/Central_bank).

The U.S. dollar was originally defined under a [bimetallic standard](https://en.wikipedia.org/wiki/Bimetallism) of 371.25 grains (24.057 g) (0.7735 troy ounces) fine silver or, from 1837, 23.22 grains (1.505 g) fine gold, or $20.67 per [troy ounce](https://en.wikipedia.org/wiki/Troy_ounce). The [Gold Standard Act](https://en.wikipedia.org/wiki/Gold_Standard_Act) of 1900 linked the dollar solely to gold. From 1934, its equivalence to gold was revised to $35 per [troy ounce](https://en.wikipedia.org/wiki/Troy_ounce). Since 1971, all links to gold have been repealed.[\[2\]](https://en.wikipedia.org/wiki/United_States_dollar#cite_note-2)

The U.S. dollar became an important international [reserve currency](https://en.wikipedia.org/wiki/Reserve_currency) after the [First World War](https://en.wikipedia.org/wiki/World_War_I), and displaced the [pound sterling](https://en.wikipedia.org/wiki/Pound_sterling) as the world's primary reserve currency by the [Bretton Woods Agreement](https://en.wikipedia.org/wiki/Bretton_Woods_Agreement) towards the end of the [Second World War](https://en.wikipedia.org/wiki/World_War_II). The dollar is the [most widely used currency](https://en.wikipedia.org/wiki/Template:Most_traded_currencies) in [international transactions](https://en.wikipedia.org/wiki/International_trade),[\[3\]](https://en.wikipedia.org/wiki/United_States_dollar#cite_note-3) and a [free-floating currency](https://en.wikipedia.org/wiki/Free-floating_currency). It is also the [official currency in several countries](https://en.wikipedia.org/wiki/International_use_of_the_U.S._dollar) and the [_de facto_ currency](https://en.wikipedia.org/wiki/De_facto_currency) in many others,[\[4\]](https://en.wikipedia.org/wiki/United_States_dollar#cite_note-4)[\[5\]](https://en.wikipedia.org/wiki/United_States_dollar#cite_note-5) with [Federal Reserve Notes](https://en.wikipedia.org/wiki/Federal_Reserve_Notes) (and, in a few cases, U.S. coins) used in circulation.

As of February 10, 2021, currency in circulation amounted to US$2.10 [trillion](https://en.wikipedia.org/wiki/Trillion), $2.05 trillion of which is in Federal Reserve Notes (the remaining $50 billion is in the form of [coins](https://en.wikipedia.org/wiki/Coins_of_the_United_States_dollar) and older-style [United States Notes](https://en.wikipedia.org/wiki/United_States_Note)).[\[6\]](https://en.wikipedia.org/wiki/United_States_dollar#cite_note-6)

As of September 20, 2023, the Federal Reserve estimated that the total amount of currency in circulation was approximately US$2.33 [trillion](https://en.wikipedia.org/wiki/Trillion).[\[7\]](https://en.wikipedia.org/wiki/United_States_dollar#cite_note-7)

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*Originally published on [Kara](https://paragraph.com/@kara-3/united-states-dollar)*