I think this was a fairly old movie, maybe from the 1970s or 1980s. It was a western, a family-friendly western. There was a girl named Jessie who ran away from home and posed as a boy named Jesse with the intention of eventually becoming a cowboy. For the majority of the movie she appears to be a boy (an older outlaw kind of character is the protagonist) and the protagonist only realizes she is a girl because at the end of the movie she comes in contact with red ants and has to wash them off.

Does anybody know the name of this movie? I can't remember it, and it's been bothering me.