[Offhand I cant remember how to do it but I do remember there is a statistical method for determine if you are doing enough tests. Offhand I would say if the # of tests is 5 times the number of cases thats probably enough.]
I would bet parts of Dallas and Austin have #s that are quite different from The rest of Texas. I grew up just West of West Texas. Id bet that region has no virus at all. The oil patch guys could probably go back to work if there was someplace to store the oil.