It is sometimes referred to as two bits because two bits of a Spanish Reales coin, which was often used in the early years of the United States, made up a quarter of that coin's value.

Half dollar coin Half Dollar

Obverse: John F. Kennedy

Reverse: Seal of the President of the United States

Diameter: 30.61 mm

Thickness: 2.15 mm

Mass: 11.34 g

Composition: 91.67% copper, 8.33% nickel

Date of first minting: 1964 (resumed in 1977)

Common reference: Half dollar, 50-cent piece

The Half Dollar of the United States, sometimes known as the fifty-cent piece, has been produced nearly every year since the inception of the United States Mint in 1794. The only U.S. coin that has been minted more consistently is the cent.

Half dollar coins are commonly used in casinos. In particular, rolls of half dollars are kept on hand in cardrooms in the United States for games requiring 50-cent antes or bring-in bets, or where the house collects a rake in increments of 50 cents (usually in low-limit seven-card stud and its variants).

The half dollar's circulation, aside from use in some casinos and movie theaters, has declined significantly. This is primarily due to a confluence of two events: the silver crisis of 1963, and the assassination of U.S. President John F. Kennedy. The value of silver had risen by 1962-63 to the point that it became worthwhile to melt down U.S. coins for their bullion value. U.S. Silver coins (those of ten cent value and above, which contained 90% silver through 1964) began to disappear from circulation, leading the United States to change to layered composition coins made of a copper core laminated between two cupro-nickel outer faces for the 1965 - present coinage years. The Kennedy half-dollar design, however, continued to be minted in a 40% silver-clad composition from 1965–1970.

Initially the Kennedy halves were hoarded for sentimental reasons and because they were recognized as the only precious metal U.S. coin remaining in circulation. By the time mintage figures could match normal demand and the coin's composition was changed to match the rest of the (non-silver) coinage in 1971, both businesses and the public had adapted to a world in which the half dollar did not generally circulate. Other uses had been found for the half-dollar section of the cash drawer. People had gotten used to depending on quarters as the major component of change.

Most coins enter circulation through the change drawers of businesses. Hardly any businesses stock their change drawers with half dollars or dollar coins, and many banks do not stock these coins and/or hand them out as normal business practice, so the coins do not see much circulation. The fact that virtually no vending machines in the United States accept half dollars does not help its circulation either.

One dollar coin One Dollar

Obverse: Sacagawea with child

Reverse: Eagle in flight

Diameter: 26.5 mm

Thickness: 2 mm

Mass: 8.1 g

Composition: 88.5% copper, 6% zinc, 3.5% Manganese, 2% nickel

Date of first minting: 2007

Common reference: Gold(en) dollar

Dollar coins have been minted in the United States in gold, silver, and base metal versions. Silver dollars, the first dollar coin issue, were minted beginning in 1794.

The term silver dollar is often used for any large white metal coin issued by the United States with a face value of one dollar; although purists insist that a dollar is not silver unless it contains some of that metal. Gold and gold-colored dollars have also been produced by the United States. The Sacagawea and Presidential dollars are usually referred to as "golden", despite not containing any gold.

Dollar coins have found little popular acceptance in modern circulation in the United States, despite several attempts since 1971 to phase in a coin in place of the one dollar bill. This contrasts with currencies of many other developed countries, where denomination of similar value is only in coin, such as the Canadian loonie and toonie, British 50 pence coin (as well as the 1 pound and 2 pound British coins), the 1 and 2 Australian Dollar coins, the 50 New Taiwan dollar coin, 100 Japanese yen coin, 1 euro coin and 2 euro coin.