I think the obvious answer is Facebook -- it's hard to imagine any other channel coming close to matching the effectiveness of Facebook for local targeting.
Snapchat is another option: you can geofence an on-demand filter with Snapchat using a map, which is pretty cool and obviously very specific. Snap filters are great if you want to target a big sports game or conference or event with a large concentration of people where the geographic boundaries matter. More info here.
TV can work for local advertising but you need to carefully manage the placements via the local affiliate / station, which can be super time consuming, and you get very little data to go on regarding demographic reach. I've never had any success with radio -- it doesn't feel like a viable channel for digital products to me.
See all at Growth-Jobs.com