While Lancaster is the epicenter for Amish, they have been moving West for a long time. Western PA and Ohio have a significant population. They seem to go where land is cheap. A lot of the Amish furniture comes from factories in Ohio.
The Ziggenfus clan are from South Western PA. They're the one's that sued the State because they thought the orange triangular signs were too much. They want reflective grey/brown signs on the back of their buggies.
Actually, it's not even close in PA, the next largest community is 10% the size & is in the center of the state...
Ohio is a different topic altogether, I'm only addressing PA as that's where @rasband is going which led to his question.
https://amishamerica.com/pennsylvania-amish/