Good ways to advertise singles group at no cost...

I ‘inherited’ the co-ordinator role of a social singles group for people in their 30s & 40s in the NY area (no secret here, I have mentioned this on this board before). We run several social events per month, no cost to attendees beyond the meal cost/greens fees/billiards fees/etc - you get the idea.
It’s former modus operandi to get new members was to advertise selected events in the free singles columns in the local daily & weekly papers - but this has dropped off considerably over the past few years as newspaper readership (especially in the under 50 category) has declined. I am posting event notices on various on-line event calendars (such as News-12, for example), but I haven’t noticed any interest coming from those areas - and Craigs List seems to be a huge black-hole -I’ve posted a number of events over the years that should appeal to key demographics, such as Billiards, Bowling, Horseback-riding etc, with no response (I used a special e-mail for reponse tracking purposes, being such a clever boi… :stuck_out_tongue: ).
So I am asking for suggestions for (well, ‘public service’ no-cost) methods of advertising, preferably on-line (we’ve tried posting flyers in diners & supermarkets over the years, with a poor response rate - and bars around here tend to be hostile to most singles groups posting fliers for events not in their bar).
Success stories and strategies are most welcome. ?

Did you try starting a Facebook group? If any of your current members are on Facebook, ask them to join the group. Then their friends and friends-of-friends might join up. Make sure you actually post messages to the group on a regular basis, or people will forget about you.