United States, 1923 AD., Monroe Doctrine centennial commemorative, San Francisco mint, ½ Dollar, KM 153.

United States, Monroe Doctrine centennial commemorative, engraver: Chester Beach, San Francisco mint, 1923 AD.,
½ Dollar (ø 30,6 mm / 12,51 g), 0.900 silver, 12,50 g. theor. mint weight, mintage 274.077 , axes coin alignment ↑↓ (180°), reeded edge,
Obv.: UNITED STATES OF AMERICA / IN GOD / WE TRUST - 1923 / S / MONROE ~ ADAMS / HALF DOLLAR , conjoined busts of former presidents James Monroe and John Quincy Adams facing left.
Rev.: MONROE DOCTRINE CENTENNIAL / 1823 - 1923 - {CB} / LOS ANGELES , stylized figures representing North and South America touch at the Panama Canal.
KM 153 .

Year / Mint Mark / Mintage
1923 / S / 274.077

The Monroe Doctrine was a U.S. foreign policy regarding domination of the American continent in 1823. It stated that further efforts by European nations to colonize land or interfere with states in North or South America would be viewed as acts of aggression, requiring U.S. intervention.[1] At the same time, the doctrine noted that the United States would neither interfere with existing European colonies nor meddle in the internal concerns of European countries. The Doctrine was issued in 1823 at a time when nearly all Latin American colonies of Spain and Portugal had achieved or were at the point of gaining independence from the Portuguese and Spanish Empires. The United States, working in agreement with Great Britain, wanted to guarantee that no European power would move in.
more on https://en.wikipedia.org/wiki/Monroe_Doctrine and https://en.wikipedia.org/wiki/Monroe_Doctrine_Centennial_half_dollar