You can imagine a farmers market is a huge hit in a community where the growing season is about 45 days long at best. The trick is to go early - as soon as you can get there after it opens at 8. It is then that you can get to your favorite bread maker and run into your good friends. Later, the tourists headed for or returning from Yellowstone descend and it is a challenge just to make it around the square.
About half of the vendors are local. That is, coming from 20 or so miles from town. Others come from Idaho and, sometimes, Montana. As the season wanes and the days and nights get colder the latter sort of hold things together. When the market closes mid September depending on the weather there is one big last day event that is not to be missed. Why? Because after that it is mostly locals and they know that the very next day it could be snowing.