That's something that's usually advertised by the establishment. I know that e.g. in St Louis both Rooster and Mike's Local Eats source their ingredients from local as much as possible

My brother is a chef at a kosher restaurant and tells me that they have to use specific suppliers. I don't know if those suppliers are 'local' but they're definitely segregated from suppliers like Sysco.

My point is there are niche restaurants, like a kosher restaurant, that may source things more locally for reasons.

Five Guys usually names where the potatoes are from, but oddly don't mention the source of the beef, veggies, etc.

Chains, by definition, are supplied by the lowest common denominator

In-N-Out can only place restaurants in certain locations due to internal supply chain limitations. I haven't confirmed it, but I wouldn't be surprised if their food was sourced locally because of it.

Swiss Chalet in Rochester and Buffalo used to source it's potatoes locally, before they closed anyway. Kraft for everything else not supplied by the chain.

me and my 30 year old information