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To examine changes in prevalence of vaginal human papillomavirus (HPV) between 2009–2010 and 2013–2014 among both vaccinated and unvaccinated U.S. women.We evaluated HPV prevalence among women 18–59 years old using cross-sectional survey data from three different cycles of the National Health and Nutrition Examination Survey. Data were stratified into four age groups (18–26, 27–34, 35–44, and 45–49 years) to examine trends over time among women of different ages in the postvaccine era. Multivariable analyses, which controlled for descriptive variables, were used to examine the prevalence of quadrivalent vaccine-type HPV by vaccination status.We observed a significant decrease in the prevalence of vaccine-type HPV among women 18–59 years of age from 2009–2010 to 2013–2014. This decline was only significant in those 18–26 years old when the sample was stratified into the four age groups. Among vaccinated 18–26 year olds, HPV prevalence remained low from 2009–2010 (3.9%) to 2013–2014 (2.0%; prevalence ratio 0.51, 95% CI 0.18–1.46). Unvaccinated women 18–26 years old also demonstrated a significant decrease over time from 19.5% in 2009–2010 to 9.7% in 2013–2014 (prevalence ratio 0.44, 95% CI 0.22–0.91). Prevalence did not significantly change among unvaccinated women 26 years old or older.The decline in HPV infections among unvaccinated 18- to 26-year-old women suggests that young women in the United States are beginning to benefit from herd immunity resulting from the introduction of the HPV vaccine.