184 Background: Political environment in the US is closely tied to state and national-level budgetary spending as well as laws and regulations that influence health. It is unclear if survival gains in cancer care differ by county political voting status. We investigated survival trends based on county level presidential voting patterns. Methods: A 5% sample of individuals diagnosed with cancer from 2001 to 2017 in the SEER-Medicare Program was linked to county level data on US presidential elections over the same period. Using the total number of votes in each party, county political environment was classified as either Democratic or Republican for the four years that followed a presidential election. Cox proportional hazards models estimated changes in survival over time, and differences by political party were assessed with interaction analysis. To account for the association between follow-up time and year of diagnosis, overall survival was censored at 3 years for individuals diagnosed in 2015 or earlier. Results: Of 100,755 individuals in our cohort from 2001-2017, 66439 (65.9%) resided in Democratic and 34316 (34.1%) in Republican counties with similar median age at diagnosis and distribution of regional/distant disease. Democratic counties had more urban-located residents (93% vs 70%). 1-year survival in both Democratic and Republican counties increased from 2001 (77% for both) to 2017 (81% Democratic, 80% Republican). 3-year survival increased in Democratic (62% in 2001 to 66% in 2015) but not in Republican counties (65% in 2001 and 2015). Compared to the 2000 election cycle, patients residing in Democratic counties had an 11% decreased risk of death (Hazard Ratio (HR) = 0.89) after the 2008 election cycle while Republican counties did not see these improvements during the same time period (Table; interaction P = 0.02). Among White patients, survival improved (HR = 0.89 for 2016 election cycle compared to 2000) in Democratic counties, but not in Republican counties (HR = 0.99 for same years, P = 0.02). However, among Black patients, survival improved in both Democratic (HR = 0.89) and Republican counties (HR = 0.89) for the same years (P = 0.87). Conclusions: Survival after cancer diagnosis in Republican voting counties has concerningly lagged behind that of Democratic voting counties following the 2008 elections coinciding with the passage of the Affordable Care Act. Our study sheds light on the sharp contrast between political policy and legislation, and rural-urban divide driving outcomes in these areas.[Table: see text]