To quantify progress towards gender parity in elected and appointed office, RepresentWomen developed the Gender Parity Index (GPI). Each year, a Gender Parity Score and grade is calculated for each of the 50 states and for the United States as a whole. The Gender Parity Score reflects women's recent electoral successes at the local, state, and national levels on a scale of 0 (if no women were elected to any offices) to 100 (if women held all elected offices). The key advantage of the GPI is that it enables comparisons to be made over time and among states.