Modern commemorative coins are issued to celebrate significant events, people, or themes in American history. The United States Mint produces these coins, often in limited quantities, making them popular among collectors. The 50-cent coins from 1991 were part of a series celebrating the 500th anniversary of Christopher Columbus's voyage, with the San Francisco mint producing special releases that feature intricate designs and reflect the era's commemorative coinage efforts. Collectors often seek these coins for their artistic value and historical significance.