My Father belonged to the UCC - 40 years ago. They were indeed mainline, and at least in the Northeast, quite numerous (I was raised Catholic, due to my Mom)
Not being terribly religious, but quite in-tune with prevailing political winds - my Dad stopped attending UCC in the 1980’s, as he said his local church had too many “hippies.”
I can only imagine what a politicized, secular cesspool it is now.
The female, lesbian "pastor" had a Darwin fish on her office door.
Yikes, I’m finding 46 Bing Search listings for UCC in this PA 20mi dia area.
Try “UCC Churches, your town, state” and see what you get. I had no idea.