The provided search result information is insufficient to offer a comprehensive answer, as it consists of website titles and navigation elements rather than the specific content of the articles. However, drawing upon general numismatic knowledge, the value of a half dollar is determined by several factors, including its rarity, series, date, mint mark, and condition.
Some of the most historically valuable half dollars come from the earliest years of the United States Mint. The 1794 Flowing Hair half dollar, being the first year of issue, is highly sought after by collectors. The 1796 and 1797 Draped Bust half dollars are even rarer, with very low mintages, making them extremely valuable, often fetching six-figure prices at auction even in lower grades.
Moving into the 19th and 20th centuries, key-date coins from various series carry significant premiums. For example, within the Seated Liberty series, coins with very low mintages like the 1878-S are quite valuable. The Barber half dollar series has several key dates, including the 1892-O with a "Micro O" mint mark. Among Walking Liberty half dollars, issues like the 1921-S, 1921-D, and 1916-S are notable for their low production numbers and are highly prized by collectors, especially in high-grade condition.
While the titles of the provided sources mention Kennedy half dollars, most coins in this series are common. However, specific issues are valuable. The 1964 Special Mint Set (SMS) Kennedy half is a rare transitional issue that commands a high price. The 1970-D is another key date because it was only issued in mint sets and not for general circulation. Additionally, any half dollar, regardless of the series, with a significant error or in pristine, top-grade condition can be exceptionally valuable.
