As the coronavirus marches from America’s coastal cities to its heartland, testing gaps in the South and Midwest are crippling efforts to contain emerging hot spots in smaller cities and rural areas.

Georgia, Michigan and Oklahoma are among the states where coronavirus outbreaks are intensifying — and where per capita testing rates are some of the lowest in the nation. While hard-hit New York was testing more than 950 for every 100,000 people as of Monday, Georgia was testing only 127 and Oklahoma 43. That raises the likelihood that these states are severely underestimating the size of their outbreaks.

The testing blindspots not only make it harder to slow the spread of disease, health officials say, but to know when it’s safe to ease social distancing measures.