Background: In the U.S., the Pap smear has become a widely practiced, effective tool for the early detection and prevention of cervical cancer. However, the total number of cervical cancer cases that have been prevented by screening is unknown, as well as the impact of screening on racial disparities. Methods: We estimated national cervical cancer incidence from 1976 to 2009 using the Surveillance, Epidemiology, and End Result database. Screening data from 1951 to 2010 were obtained from literature and National Cancer Institute Progress Reports. We examined trends in early (localized) and late (regional, distant) stage cancer incidence and estimated the number of cancers prevented due to screening over the past three decades. Race was categorized as white, black, and other (Asian/Pacific Islander, Alaskan Native, and American Indian). Results: After rising steadily from 1951-1981, the percentage of all adult women who received cervical cancer screening stabilized at 71.7% in 1982 to 73.8% in 2010. Overall, from 1976 to 2009, there was a significant decrease in the incidence of early stage cervical cancer, from 10.2 to 5.4 cases per 100,000 women (p < .001). Late stage disease incidence also decreased, from 5.2 to 3.7 cases per 100,000 women (p < .001). After adjusting for “pre-screening era” rates of cervical cancer, we estimate that Pap smears were associated with a reduction of between 105,000 to 492,000 cases of cervical cancer over the past three decades in the U.S. The combined incidence among black women decreased from 26.9 to 9.7 cases per 100,000 women (p < .001), a greater decline compared to that of white women (13.7 to 8.5 cases per 100,000, p < .001), and women of other races (16.0 to 7.4 cases per 100,000, p < .001). Conclusions: We estimate that a large number of early and late stage cervical cancers were prevented, and the racial disparity in cancer rates was reduced during an era of increased screening. Given disparate access to the HPV vaccine, it will be important to continuously assess national cervical cancer incidence to measure the additional benefit of the vaccine against the known benefit of screening, and to ensure equal access and outcomes for all women.