I haven't tracked things closely, so I'm not sure where Cornell & Diehl is currently located. For years they were in Morganton, N.C., and may still be there, but the business was purchased by the smokingpipe.com organization and, at one time, it was thought that they'd move down to S.C. near the SP location. So before you go looking for C&D in Morganton, or in S.C. for that matter, better confirm where they are. I'd be interested to know, too!
Just an aside, while down in Morganton visiting a free range pork farm for a story (I wasn't reporting, just doing the driving) I asked several of the locals about C&D and no one had ever heard of it, so they were somewhat low profile, I guess. I thought I might visit the state's mother church of pipe tobacco blending, but didn't.