Objectives. We examined regional variation in tooth loss in the United States from 1999 to 2010. Methods. We used 6 waves of the Behavioral Risk Factor Surveillance System and data on county characteristics to describe regional trends in tooth loss and decompose diverging trends into the parts explained by individual and county components. Results. Appalachia and the Mississippi Delta had higher levels of tooth loss than the rest of the country in 1999. From 1999 to 2010, tooth loss declined in the United States. However, Appalachia did not converge toward the US average, and the Mississippi Delta worsened relative to the United States. Socioeconomic status explained the largest portion of differences between regions in 1999, but a smaller portion of the trends. The Mississippi Delta is aging more quickly than the rest of the country, which explains 17% of the disparity in the time trend. Conclusions. The disadvantage in tooth loss is persistent in Appalachia and growing in the Mississippi Delta. The increasing disparity is partly explained by changes in the age structure but is also associated with behavioral and environmental factors.