And then, waiting in the wings, are

Westering Women: westering women and the frontier experience, 1800-1915, by Sandra L. Myers
Faith and Betrayal: a pioneer woman's passage in the American West, by Sally Denton
The Doctor Wore Petticoats: women physicians of the Old West, by Chris Enss
A Lady's Life in the Rocky Mountains, by Isabella Bird (started, must finish)
Women and Indians on the Frontier, 1825-1915, by Glenda Riley

This is not a study of women in the American West, it just happened that way.