Objective: There is a growing body of literature raising concerns about the long-term durability of endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs), suggesting that long-term outcomes may be better after open AAA repair. However, the data investigating these long-term outcomes largely originate from early in the endovascular era and therefore do not account for increasing clinical experience and technologic improvements. We investigated whether 4-year outcomes after EVAR and open repair have improved over time. Methods: We identified all EVARs and open repairs for intact infrarenal AAA within the Vascular Quality Initiative database (2003-2018). We then stratified patients by procedure year into treatment cohorts of four years: 2003-2006, 2007-2010, 2011-2014, and 2015-2018. We used Kaplan-Meier analysis and Cox proportional hazards models to assess whether the survival after EVAR or open repair changed over time. In addition, we propensity matched EVAR and open repairs for each time cohort to investigate whether the relative survival benefit of EVAR over open repair changed over time.Results: We included 42,293 EVARs (increasing from 549 performed between 2003 and 2006 to 25,433 between 2015 and 2018) and 5189 open AAA repairs (increasing from 561 to 2306). Four-year survival increased for the periods 2003-2006, 2007-2010, 2011-2014, and 2015-2018 after both EVAR (76.6% vs 79.7% vs 83.5% vs 87.3%; P < .001) and open repair (82.2% vs 85.8% vs 87.7% vs 88.9%; P = .026). After risk adjustment, compared with 2003-2006, hazard of mortality up to 4 years after EVAR was lower for those performed between 2011 and 2014 (hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.59-0.87; P = .001) and for those performed between 2015 and 2018 (HR, 0.56; 95% CI, 0.46-0.68; P < .001). In contrast, the risk-adjusted hazard of mortality was similar between open repair cohorts (2011-2014: HR, 0.81 [95% CI, 0.61-1.08; P = .15]; and 2015-2018: HR, 0.86 [95% CI, 0.64-1.17; P = .34]). Finally, in matched EVAR and open repairs, there was no difference in mortality in the first three cohorts, whereas the hazard of mortality was lower for the 2015-2018 cohort (HR, 0.65; 95% CI, 0.51-0.84; P = .001).Conclusions: Four-year survival improved in more recent years after EVAR but not after open repair. This finding suggests that midterm outcomes after EVAR are improving, perhaps because of technologic improvements and increased experience, information that should be considered by surgeons and policymakers alike in evaluating the value of contemporary EVAR and open AAA repair.