Cervical cancer screening rates are suboptimal in the US. Population-based assessment of reasons for not receiving screening is needed, particularly among women from historically underserved demographic groups. To estimate changes in US Preventive Service Task Force guideline-concordant cervical cancer screening over time and assess the reasons women do not receive up-to-date screening by sociodemographic factors. This pooled population-based cross-sectional study used data from the US National Health Interview Survey from 2005 and 2019. A total of 20 557 women (weighted, 113.1 million women) aged 21 to 65 years without previous hysterectomy were included. Analyses were conducted from March 30 to August 19, 2021. Sociodemographic factors, including age, race and ethnicity, sexual orientation, rurality of residence, and health insurance type. Primary outcomes were US Preventive Services Task Force guideline-concordant cervical cancer screening rates and self-reported primary reasons for not receiving up-to-date screening. For 2005, up-to-date screening was defined as screening every 3 years for women aged 21 to 65 years. For 2019, up-to-date screening was defined as screening every 3 years with a Papanicolaou test alone for women aged 21 to 29 years and screening every 3 years with a Papanicolaou test alone or every 5 years with high-risk human papillomavirus testing or cotesting for women aged 30 to 65 years. Population estimation included sampling weights. Among 20 557 women (weighted, 113.1 million women) included in the study, most were aged 30 to 65 years (16 219 women; weighted, 86.3 million women [76.3%]) and had private insurance (13 571 women; weighted, 75.8 million women [67.0%]). With regard to race and ethnicity, 997 women (weighted, 6.9 million women [6.1%]) were Asian, 3821 women (weighted, 19.5 million women [17.2%]) were Hispanic, 2862 women (weighted, 14.8 million women [13.1%]) were non-Hispanic Black, 12 423 women (weighted, 69.0 million women [61.0%]) were non-Hispanic White, and 453 women (weighted, 3.0 million women [2.7%]) were of other races and/or ethnicities (including Alaska Native and American Indian [weighted, 955 000 women (0.8%)] and other single and multiple races or ethnicities [weighted, 2.0 million women (1.8%)]). In 2019, women aged 21 to 29 years had a significantly higher rate of overdue screening (29.1%) vs women aged 30 to 65 years (21.1%; P < .001). In both age groups, the proportion of women without up-to-date screening increased significantly from 2005 to 2019 (from 14.4% to 23.0%; P < .001). Significantly higher rates of overdue screening were found among those of Asian vs non-Hispanic White race and ethnicity (31.4% vs 20.1%; P = .01), those identifying as LGBQ+ (gender identity was not assessed because of a small sample) vs heterosexual (32.0% vs 22.2%; P < .001), those living in rural vs urban areas (26.2% vs 22.6%; P = .04), and those without insurance vs those with private insurance (41.7% vs 18.1%; P < .001). The most common reason for not receiving timely screening across all groups was lack of knowledge, ranging from 47.2% of women identifying as LGBQ+ to 64.4% of women with Hispanic ethnicity. Previous receipt of a human papillomavirus vaccine was not a primary reason for not having up-to-date screening (<1% of responses). From 2005 to 2019, among women aged 30 to 65 years, lack of access decreased significantly as a primary reason for not receiving screening (from 21.8% to 9.7%), whereas lack of knowledge (from 45.2% to 54.8%) and not receiving recommendations from health care professionals (from 5.9% to 12.0%) increased significantly. This cross-sectional study found that cervical cancer screening that was concordant with US Preventive Services Task Force guidelines decreased in the US between 2005 and 2019, with lack of knowledge reported as the biggest barrier to receiving timely screening. Campaigns addressing patient knowledge and provider communication may help to improve screening rates, and cultural adaptation of interventions is needed to reduce existing disparities.