There is debate about the value of preventive visits in primary care, and multiple policy trends during the past fifteen years may have influenced the likelihood of US adults undergoing preventive primary care visits. Using nationally representative, serial cross-sectional data on adult visits to primary care physicians from the 2001-19 National Ambulatory Medical Care Survey, we characterized temporal trends in the proportion of primary care visits with a preventive focus and the differential characteristics of these visits. Based on a sample of 139,783 unweighted (5,902,144,258 weighted) US primary care visits, we found that the proportion of primary care visits with a preventive focus increased between 2001 and 2019 (12.8 percent of visits in 2001-02 versus 24.6 percent in 2018-19; [Formula: see text]), with the greatest rate of increase seen for people with Medicare. Primary care visits with a preventive focus involved more time spent with the physician and addressed fewer reasons for the visit compared with problem-based visits. At least one of the following was significantly more likely to occur during a preventive visit than a problem-based visit: counseling provision, ordering of preventive labs, or ordering of a preventive image or procedure. Our findings demonstrate a relative increase in preventive versus problem-based visits in primary care and suggest the importance of enhanced insurance coverage in influencing preventive care delivery trends.