“The US has conducted about 72 tests per 1,000 people, according to Our World In Data. That’s a lower rate than Portugal or Russia or Iceland and about the same as Australia and Italy. Good but hardly warranting “greatest of all time” designations. The number of tests in the US that are coming back positive also suggests we are still not adequately surveilling Covid-19 compared to European countries.”
…
“When you conduct more tests, you would expect the positive test rate to go down, because along with some more positive tests, you would get many more negative ones. So experts are concerned because in states like Arizona and Florida and Texas, the positive test rate is actually increasing. That is what suggests increased spread of Covid-19 is behind some of rising case numbers — not simply more tests being conducted.”
https://www.vox.com/2020/6/18/21295826/coronavirus-us-update-trump-wsj-interview-masks-tests