Commemerative Question

They are legal tender, but it's my understanding that most if not all of them were sold direct to collectors, dealers, or the group that organized that the coins be struck, to be sold at a premium above face value (for half-dollars, typically between $1 and $2). People would be understandably reluctant to take a coin they had paid a premium for and spend it for face value, so it rarely happened. Unsold coins were returned to the mint, but as far as I'm aware these remainders were never simply bagged up with the rest of the half-dollars and sent into circulation.

On the other hand, the Great Depression happened at about he same time as many of the commemorative coins came out - some pre-Depression types no doubt did indeed get spent and circulated during the tough times. Afterwards, World War II might also have seen some people be more concerned with buying what they needed rather than saving special coins.

Finally, some have been used as "pocket-pieces", accruing considerable wear in an effort to undo a botched cleaning job, a staple scratch or some other damage.

Due to several times lately of poor economy, crime has increased substantially. One of the major increases is in home robberies, people getting robbed to and/or from a coin store or show. Coin dealers being robbed at shows and at their stores. There has been several such home robberies in my block where I live. Most criminals have little knowledge of Numismatics so to them a coin is a coin. Many realize that some of what they stole is strange so they just dump them into counting machines anywhere. Some even take them to banks in bags or rolls.
Regardless of how they get rid of the stolen coins, they all get circulated.

The Oregon Trail is a truly beautiful commemorative half dollar. Mintage began in 1926 and continued off and on until 1939. The 1926 and 1926 s are the most common and are found in a variety of condition. Later issues especially the 1939's are very low mintage and command a high price accordingly.