The governor of Kansas made an executive order on July 3rd, 2020 for a state mask mandate for public spaces, and by August 11th,2020, 24 of Kansas’ 105 counties followed the mandate or adopted their own mandate while 81 counties opted out of the state mandate and did not adopt their own mandate. Segmented regression was used to analyze changes in COVID-19 incidence before and after the mask mandate among mandated and nonmandated counties. By August 17-23, COVID-19 incidence had decreased among mandated counties (net decrease of 6% from 17 to 16 cases per 100,000) and increased among nonmandated counties (net increase of 100% from 6 to 12 cases per 100,000). Countywide mask mandates may have contributed to the decrease in transmission in counties adopting the mask mandates; this study adds to the body of evidence that community-level mitigation strategies that emphasize wearing masks can help reduce the transmission of SARS-CoV-2.