Recent closures of rural obstetric units and entire hospitals have exacerbated concerns about access to care for more than twenty-eight million women of reproductive age living in rural America. Yet the extent of recent obstetric unit closures has not yet been measured. Using national data, we found that 9 percent of rural counties experienced the loss of all hospital obstetric services in the period 2004–14. In addition, another 45 percent of rural US counties had no hospital obstetric services at all during the study period. That left more than half of all rural US counties without hospital obstetric services. Counties with fewer obstetricians and family physicians per women of reproductive age and per capita, respectively; a higher percentage of non-Hispanic black women of reproductive age; and lower median household incomes and those in states with more restrictive Medicaid income eligibility thresholds for pregnant women had higher odds of lacking hospital obstetric services. The same types of counties were also more likely to experience the loss of obstetric services, which highlights the challenge of providing adequate geographic access to obstetric care in vulnerable and underserved rural communities.