Individuals seeking a single test, or more information about Covid-19 / Coronavirus, can consider these online resources:
U.S. Department of Health & Human Services (HHS) List of COVID-19 Testing Sites
https://www.hhs.gov/coronavirus/community-based-testing-sites/index.html
Centers for Disease Control and Prevention (CDC) Coronavirus Resources
https://www.cdc.gov/coronavirus/2019-nCoV/index.html
Google's Coronavirus Information & Insights
https://www.google.com/intl/en_us/covid19/
USA Coronavirus (Covid-19) Government Resources
https://www.coronavirus.gov/