Specifications

Denomination: Half dollar
Designer: Chester Beach
Weight: 12.5 g
Diameter: 30.61 mm
Edge: Reeded

Conjoined busts of James Monroe and John Quincy Adams on the 1923-S Monroe Doctrine Centennial half dollar. Image: Wikimedia Commons (public domain).

The 1923-S Monroe Doctrine Centennial half dollar was a Hollywood fundraiser whose film exposition flopped — nine-tenths of the mintage went into circulation, making it one of the few classic commemoratives routinely found worn. The 2015 Red Book lists it at $75 in MS-60 (Wikipedia).

History

In 1922 the motion picture industry was reeling from scandals — the manslaughter trials of “Fatty” Arbuckle (acquitted) and the shooting death of director William Desmond Taylor — and executives wanted a respectable publicity vehicle: an exposition in Los Angeles in mid-1923. To get Congress to authorize a fundraiser coin, they hitched the fair to the 100th anniversary of the Monroe Doctrine (Wikipedia).
California Congressman Walter Franklin Lineberger introduced the bill on December 18, 1922; despite objections (Vermont’s Frank Greene called such coinage “harlotry”), it was enacted January 24, 1923, authorizing up to 300,000 half dollars, with the Los Angeles Clearing House given the exclusive right to buy them at face value (Wikipedia).
Chester Beach designed the coin at the suggestion of James Earle Fraser; the reverse — two draped female figures as North and South America touching hands at the Panama Canal — closely resembled the seal Raphael Beck had designed for the 1901 Pan-American Exposition, and Beck complained to the Mint Director on July 23, 1923, that Beach had plagiarized his copyrighted 1899 work. Beach and Fraser denied any impropriety (Wikipedia).
The American Historical Revue and Motion Picture Industry Exposition ran July 2–August 4, 1923, but drew about 300,000 visitors against a hoped-for million and was a financial failure. Only about 27,000 of the 274,077 half dollars sold at $1; banks released the rest into circulation at face value (Wikipedia; ANA).
This entry is part of the Classic U.S. Commemoratives series.

What is it worth

The 2015 edition of R.S. Yeoman’s A Guide Book of United States Coins lists the coin at $75 in uncirculated MS-60 (Wikipedia).
Circulated pieces are common — most survivors show wear, and many were spent during the Depression — so uncirculated examples carry the premium; an exceptional specimen certified MS-67 sold at auction for $29,900 in 2009 (Wikipedia).

What drives the premium

Condition rarity: unlike most classic commemoratives that collectors saved, the bulk of this issue circulated, so genuinely uncirculated coins are far scarcer than the 274,077 mintage suggests (Wikipedia).
Surface problems: many specimens were brightened or otherwise treated to look less worn; these, like other circulated pieces, are worth less — original surfaces matter (Wikipedia).
Design reputation: the coin’s shallow relief and “uninspired” allegory were panned (Pike; Vermeule, via Wikipedia), which has kept collector demand modest and prices approachable relative to other 1920s commemoratives.

Specifications

Composition: 90% silver, 10% copper (Wikipedia)
Weight: 12.5 g (Wikipedia)
Silver content: 0.36169 troy oz (Wikipedia)
Diameter: 30.61 mm (Wikipedia)
Thickness: 2.15 mm (Wikipedia)
Edge: Reeded (Wikipedia)
Alignment: Not verified in consulted references
Designer: Chester Beach (Wikipedia)
Mint: San Francisco (S, under the date), 1923 only (Wikipedia)

Collector notes

Mintage context: 274,077 struck at San Francisco in May and June 1923, including 77 pieces set aside for the 1924 Assay Commission; about 27,000 sold at a premium, the rest entered circulation (Wikipedia; ANA).
Obverse details: conjoined busts of James Monroe and John Quincy Adams facing left, with the S mintmark under the date. Reverse details: North America as a draped figure holding the laurel of peace, reaching across to touch hands with South America (carrying a horn of plenty) at the Panama Canal; a scroll and quill pen — symbolizing the doctrine — sit between the dates 1823 and 1923; “MONROE DOCTRINE CENTENNIAL” arcs across the top and “LOS ANGELES” appears at the bottom; Beach’s circular CB monogram is at four o’clock (Wikipedia; ANA).
Faint lines in the reverse field represent ocean currents (the Gulf Stream is at upper right), possibly symbolizing trade routes between the continents (Wikipedia).