The last formal place I knew for that had been started as a non-profit group basically funded by a wonderful man who’d been the ‘Dial an Atheist’ guy for years in my hometown of Portland, OR. I’d moved too far from the city to easily attend most functions … and this was in the days where women atheists were not to be found - Though ‘Jerry’s Daughter’ broke the mold, suing the Boy Scouts for discriminating against her atheist son! She eventually became our Prez … a dozen guys lead by one fantastic woman..
It, United States Atheists, has not been active for years ... and that was only ‘one town’ of many. I find most of my ‘like thinkers’ amid the local Democrats, attend their meetings and hangouts.. Of course there are still religious apologists … but just enough of us not’s to grin big, and laugh later… Our people are scattered, but it’s like finding gold when we meet
It's been tried in my town and it didn't seem to catch on, apparently after everyone agreed that the very idea of god(s) was a crock of shit, the conversation faded. This would make a great sign for you to use if you decide to set up such a space.