Background: Rural Americans have less access to care than urban Americans. Preventable acute care use is a marker of unmet ambulatory healthcare needs, but little is known about how such utilization has differed between rural and urban areas over time. Objective: Compare preventable emergency department (ED) visit and hospitalization rates among rural versus urban residents over the past decade. Design: Observational study using a validated algorithm to compute age-sex-adjusted rates per 100,000 individuals of preventable ED visits and hospitalizations. Differences in overall, annual, and condition-specific rates for rural versus urban residents were assessed and linear regression was used to assess 10-year trends. Setting: Nationwide Emergency Department Sample, National Inpatient Sample, and US Census, 2008–2017. Participants: US adults, an annual average of 241.3 million individuals. Measurements: Preventable ED visits and hospitalizations. Results: Compared to urban residents, rural residents had 45% higher rates of preventable ED visits in 2008 (3003 vs. 2070 per 100,000, adjusted difference [AD]: 933; 95% CI: 928–938) and 44% higher rates of preventable ED visits in 2017 (3911 vs. 2708 per 100,000, AD: 1202; 95% CI: 1196–1208). Rural residents had 26% higher rates of preventable hospitalizations in 2008 (2104 vs. 1666 per 100,000, AD: 439; 95% CI: 434–443) and 13% higher rates in 2017 (1634 vs. 1440 per 100,000, AD: 194; 95% CI: 190–199). Preventable ED visits increased more in absolute terms in rural versus urban residents, but the percentage increase was similar (30% vs. 31%) because rural residents started at a higher baseline. Preventable hospitalizations decreased at a faster rate (22% vs. 14%) among rural versus urban residents. Limitations: Observational study; unable to infer causality. Conclusions: Rural disparities in acute care use are narrowing for preventable hospitalizations but have persisted for all preventable acute care use, suggesting unmet demand for high-quality ambulatory care in rural areas.