Maternal mortality has steadily risen in the United States over the last several decades, a trend unobserved in other developed countries. Whether the uptick in maternal mortality in the U.S. is due to improvements in reporting of pregnancy-related deaths or actual increases in maternal death is unknown. The researcher hypothesizes that several factors other than reporting changes (e.g. increasing Caesarean section rates, changes in maternal age distribution) are associated with the rise in pregnancy-related deaths in the U.S. Using a difference-in-differences approach and mortality data from the National Vital Statistics System, this research illustrates the leading causes of maternal mortality and how cause-specific maternal mortality has evolved over the last 50 years at the national and state level, with a focus on differences among socioeconomic and demographic variables. The public health implications of this work are illustrating trends in maternal mortality at the national and state level over a long period of time, and informing policy and program development to improve health outcomes for women during and after pregnancy and delivery.