Whenever I post about the Oregon Trail Memorial Half Dollar (or someone else does), it's essentially a given that one or more CCF'ers will add comment(s) about the beauty of the coin's designs and how they surpass other US commemorative coins.
Why is the Oregon Trail Memorial Half Dollar held in such universally high regard? I think a few key factors are at play:
1. Broad theme: The coin is not tied to a specific date or personality and the event it commemorates occurred over decades across thousands of miles of undeveloped territory. With such an "open" theme {lots of potential subjects) from which to work, many attractive/artisitc themes can be explored - IMO, much more so than when an artist is faced with "Design a coin to commemorate "Person X."
2. Talented artists: The husband-wife team of
James Earle Fraser and
Laura Gardin Fraser was comprised of two highly-talented artists with demonstrated skill and experience in medallic art (including coins). Also, James was a prolific producer of western-themed artwork (sculpture, medals, etc.). Give a pair of talented artists "free reign" in the design details of a coin/medal, chances are good that the final product they create will be a good one! (IMO)
3. Popular / Romantic Subject: Aided by the benefit of looking back at it through the lens of time, the difficult life (and often deadly experiences) of the pioneers who explored and settled the vast expanse of the US West became a romantic story of adventure and heroic deeds. Such baseline positive feelings about a subject create a great starting point for a piece of art!
Those are a few of my initial thoughts - What say you?
1926 Oregon Trail Memorial Half Dollar

For more of my topics on commemorative coins and medals, including much more on the Oregon Trail half dollar, see:
Commems Collection.