Does anyone have any recommendations for RT-PCR tests in the US? I was also wondering if the test needed to be done specifically in a lab? I found a local clinic that offers the test but this is done in their office not at a lab. Does that make a difference?

Question about the PCR covid Test. I had my test done as I'm flying on Sunday. The Dr sent a letter that just stated my PCR covid test was negative and then a bunch of blah blah blah if you have symptoms you should stay home etc. I'm just wondering is this letter enough for my Negative Covid Test or do I need something that looks more like the lab results?