Where is the Ozark Trail located
The Ozark trail is a hiking trail located in Missouri.  If you've ever been to Branson, you weren't too far from it.
OK.     Branson is primarily known for country music, right?
Yes, that is right. There is also a Ozarks Auto trail that runs from  St. Louis to El Paso texas and Santa fe, New Mexico
How long is that trail, in miles?
Probably about a thousand, I am guessing.  But the hiking trail goes from St. Louis to Arkansas, or will when it is finished.
When did they start working on the trail?
The auto trail is based on a trail that predates the automobile, so a long time ago.