https://www.giveapint.org/ Locations in Pottstown/Exton, plus St Luke's Hospital
Red Cross, lots coming up: https://www.redcrossblood.org/give.html/drive-results?dt=WB:...
Supposedly CHOP has locations too. They do wonderful work.
I grew up in lower bucks. There were no dedicated blood centers. Before I was 22 I had never donated at anything but a mobile bloodbank. My parents hauled themselves to mobile blood banks whenever they wanted to do it. The first actual dedicated blood center I donated at was blood centers of the pacific in San Francisco. I was shocked that someone would actually build a dedicated site just for donating blood. But then later I saw Oregon did it too.
Also there's this: https://www.inquirer.com/health/blood-donation-shortage-phil...
There is also no selection bias. I said that in the 90's there were several near West Chester and KoP. You say ChesCo is the wealthiest. Wealth in ChesCo is entirely concentrated within the KoP; West Chester; and Valley Forge area. Which would be accurate to what I said. I did not grow up anywhere near there, rather in a very poor region, which is most of the county. It is a large county.
Then I moved to east coast, and there is basically none of that infrastructure, you have to find a mobile blood bank or be aware of some event or community site that sometimes hosts them. I'm bad at that kind of community awareness, so the upshot is I haven't donated once in the 15 years I've lived here. Always surprised by that since there are so many more people on the east coast, I'm not sure where all the blood is coming from since they are so bad about getting people to do regular donations.