Every year in the United States more than 12,000 women are diagnosed with cervical cancer, a disease principally caused by human papillomavirus (HPV). Bivalent and quadrivalent HPV vaccines protect against 66% of HPV-associated cervical cancers, and a new nonavalent vaccine protects against an additional 15% of cervical cancers. However, vaccination policy varies across states, and migration between states interdependently dilutes state-specific vaccination policies. To quantify the economic and epidemiological impacts of switching to the nonavalent vaccine both for individual states and for the nation as a whole, we developed a model of HPV transmission and cervical cancer incidence that incorporates state-specific demographic dynamics, sexual behavior, and migratory patterns. At the national level, the nonavalent vaccine was shown to be cost-effective compared with the bivalent and quadrivalent vaccines at any coverage despite the greater per-dose cost of the new vaccine. Furthermore, the nonavalent vaccine remains cost-effective with up to an additional 40% coverage of the adolescent population, representing 80% of girls and 62% of boys. We find that expansion of coverage would have the greatest health impact in states with the lowest coverage because of the decreasing marginal returns of herd immunity. Our results show that if policies promoting nonavalent vaccine implementation and expansion of coverage are coordinated across multiple states, all states benefit both in health and in economic terms.uman papillomavirus (HPV) is the most prevalent sexually transmitted infection in the United States (1). Although more than 100 types of HPV have been identified, HPV-16 and HPV-18 are responsible for 66% of cervical cancers (2). Two vaccines, Gardasil (4vHPV) and Cervarix (2vHPV), were approved by the Food and Drug Administration in 2006 and 2009, respectively. Both of these vaccines are highly efficacious against HPV-16 and HPV-18 and are partially efficacious against other non-vaccine-targeted oncogenic serotypes (2, 3). Licensed in 2014, Gardasil-9 (9vHPV) is a new vaccine that elicits immunity to five additional oncogenic serotypes, extending protection to 80% of cervical cancers (2, 4). In 2007, the Centers for Disease Control and Prevention (CDC) recommended HPV vaccination for all girls and women aged 9-26 y (5). In 2011, this recommendation was extended to males to reduce transmission (3). In 2015, the CDC recommended that females aged 11-26 y be vaccinated with any of the three available vaccines and that males aged 11-21 y receive either 4vHPV or 9vHPV (2). Although CDC contract and private sector prices vary, the new vaccine, at a per-dose cost of $126, is approximately $13 more costly than 4vHPV and $18 more costly than 2vHPV (SI Appendix).HPV vaccination has been recommended nationwide with funding to enhance coverage provided by the CDC Prevention and Public Health Fund (PPHF) (6). Vaccine cost, the availability of subsidies, and the supplementing of federal support with state and local funds have b...