Using data from 73.6% and 97.7% of US counties respectively, the authors assessed the association between mask mandates and on-premises restaurant dining policies on COVID-19 case and death rates during the first 100 days after implementation. Within the first twenty days after initiating mask mandates, there was a 0.5 percentage point decrease in COVID-19 daily case rates and a 0.7 percentage point decrease in COVID-19 daily mortality rates (p = 0.02 and p=0.03, respectively). Daily case and mortality rates continued to decrease at significantly higher rates 21-40, 41-60, 61-80, and 81-100 days after initiating mask mandates (p<0.01 for all). While there were no statistically significant associations between reopening restaurant dining and case or death rates from 1-20 or 21-40 days after implementation, there were statistically significant increases in COVID-19 case rates from 41-100 days after implementation, with increases of 0.9, 1.2, and 1.1 percentage points for each of those three time periods (p=0.02, p<0.01, p=0.04, respectively). In addition, death rates increased 2.2 and 3.0 percentage points during 61-80 and 81-100 days post implementation (p<0.01 for both). Although one cannot conclude a causal relationship between opening restaurants and increasing case and death rates, this does support existing research and CDC recommendations that community transmission can be prevented via mask mandates and in-restaurant dining restrictions as components of a county’s comprehensive strategy.