Collectible coins are often sought after by numismatists for their historical significance, rarity, and aesthetic appeal. The United States One Dollar coins, including various series such as the Sacagawea and Presidential dollars, are popular among collectors. Roosevelt Dimes, first issued in 1946, are collected for special mintages, proof versions, and their silver content in earlier years. The 1981 Roosevelt Dime, minted in both Philadelphia and Denver, is often noted for its standard copper-nickel composition and is less sought after than its silver predecessors.