PURPOSE: Though urban-rural disparities in COVID-19 vaccination coverage was documented at a point of time, little is known on the evolution of vaccination uptake over time. This study, using individual level time-to-event data, intend to assess the differences in monthly progression of vaccination uptake among U.S. adults by urban/rural residence. DESIGN: Survival analysis. SETTING: Urban and rural areas in 29 U.S. states. SUBJECTS: 135,969 adults aged 18+ years. MEASURES: Time (in months) to receive the first dose of COVID-19 vaccine since the U.S. Food and Drug Administration (FDA) Emergency Use Authorization of Pfizer-BioNTech- and Moderna- COVID-19 Vaccine in December 2020. ANALYSIS: Kaplan-Meier survivor functions and stratified Cox proportional hazard models were estimated for the event of being vaccinated by urban/rural residence for 25 months starting from December 2020. Monthly survival probabilities for urban- and rural- adults were further assessed within certain demographic and socioeconomic groups. RESULTS: We found a gradual divergence of COVID-19 vaccination uptake in favor of urban adults, which was robust across sex, age groups, race and ethnicity, education, and income levels. In April 2021, after vaccine eligibility was expanded, 42.2% adults in urban and 53.3% adults in rural areas were unvaccinated. While only 19.3% urban adults remained unvaccinated in December 2022, this rate was 32.5% among rural adults. Compared to their urban counterparts, rural adults were 0.77 (95% CI: 0.76 - 0.79) times as likely to receive the first dose of COVID-19 vaccine. CONCLUSIONS: Time-to-event analysis of vaccination against COVID-19 indicated a lower uptake among rural adults, which was persistent across different demographic and socioeconomic groups.