Between 1870 and 1930, women physicians in the American West played key roles in shaping the region’s health politics and medical geography. Women doctors became influential actors in the region precisely because the rapid growth of the American West coincided with the rise of progressivism, scientific medicine, maternalism, and early state suffrage laws. It was this simultaneity of events that produced a unique environment for women physicians to take a lead role in constructing the region’s medical and public health landscape. Focusing on themes of medical imperialism, reproductive politics, and public health, “Medical Frontiers” argues that women physicians leveraged the fluidity inherent within frontier spaces to practice medicine, participate in politics, and design the public health infrastructure of the developing American West. Steeped in medical knowledge and maternalist ideologies, these enfranchised doctors positioned themselves as vanguards in the movement for modern public health and reproductive medicine. They believed that they possessed the necessary qualities over their male colleagues to make moral public health decisions. What constituted “moral,” however, was contested and fraught. Many white women physicians used their professional and political power to police marginalized communities through a moralist medicine philosophy and policies of reproductive surveillance. Their work in institutional incarceration, eugenics, and oppressive public health legislation created a medical geography in the region underlined by race science, Protestant moralism, and principles of settler colonialism. Not all medical women in the region agreed with this approach. The small numbers of physicians of color, along with some leftist physicians, pushed back on moralist medicine and reproductive surveillance by supporting access to abortion services and racial and class equality in public health. Western women doctors held diverse opinions on medicine and public health, and they advocated for radically different policies from various positions of power. “Medical Frontiers” examines the wide spectrum of health politics among these women, the ways in which they performed, advocated, and debated these various ideologies, how their work reinforced or fought against racial and class hierarchies, and the significant impact they had on the institutional and legal development of the region and beyond.