Table 2 presents the descriptive statistics for the 925 counties in 2005 and 2010 (1,850 total observations). To account for non-normality, Wilcoxon signed-rank tests were used to describe changes in the covariates from the year 2005 to 2010. All variables changed significantly (P < 0.001) in the 5-year lapse between observations. The fluoridation chemical covariates were not time-varying. There were 155 counties where only sodium fluoride was used, 536 where only fluorosilicic acid was added and 54 where sodium fluorosilicate was the only additive. A minority (19%) of counties used more than one additive: 102 where sodium fluoride and fluorosilicic acid were used, 28 where sodium fluoride and sodium fluorosilicate were used, 33 where fluorosilicic acid and sodium fluorosilicate were used and 16 where all three additives were resourced. As a consequence of this minority of multiple additives, all three fluoridation chemicals were retained as binary variables in the regressions. Finally, per capita water consumption (UL/LL) decreased, whereas poverty, obesity and physical inactivity increased significantly (P < 0.001).