A dozen states recorded record highs in new daily cases between June 19 and June 22.
New daily cases are rising in 26 states, with eight of these states increasing by 100 percent or more.
They tended to open almost a month after the states with the highest increases in Covid-19 cases.
South Korea had its first Covid-19 case about the same time as the United States.
However, By the time South Korea reported 204 confirmed cases on February 21, the country had conducted a total of 16,400 tests.