Background <p>Limited access to primary care may disproportionately affect older adults, who often have greater chronic disease management and care coordination needs. However, little is known about the effect of having a primary care practitioner (PCP) on longevity in the aging population.</p> Objective <p>To examine the association of having a usual source of primary care with mortality and life expectancy among US adults aged 65 and older.</p> Design <p>Retrospective cohort study, using nationally representative data from the 2000 and 2005 cohorts of the National Health Interview Survey linked with National Death Index records through 2019.</p> Participants <p>All respondents aged 65 to 84 (<i>n</i> = 10,873, weighted <i>n</i> = 16,484,914).</p> Interventions/Exposures <p>Having a usual source of primary care.</p> Main Measures <p>Using a Cox proportional hazards model, we examined the association between exposure to primary care and 15-year mortality, adjusting for sociodemographic factors and respondent life expectancy (using a validated index). We also used this model to generate survival curves by exposure to primary care and computed median survival times for each group.</p> Key Results <p>Overall, 60.3% of respondents were female, 83.6% were non-Hispanic White, and 6.4% (<i>n</i> = 739, weighted <i>n</i> = 1,056,554) did not have a usual source of primary care. Use of primary care was associated with a lower 15-year mortality risk (aHR: 0.84, 95% CI: 0.72–0.98). Median survival time was also at least 2.1&#xa0;years longer among those who used primary care (&gt; 15&#xa0;years) compared to those who did not (12.9&#xa0;years).</p> Conclusions <p>We found that primary care use is associated with greater survival among older adults. As the population of adults aged 65 + is growing rapidly, investing in primary care is essential for the health of US older adults.</p>