Ohio can make an argument for being one of the best, as can New York and New Jersey. Some argue for California (based on sheer numbers alone) and Florida, but they aren't quite there yet, in my opinion.
I was born and raised in PA, and was involved with wrestling from about the age of 2 until 18. My dad took me to dual meets and tournaments as soon as I was out of diapers, and I was introduced to youth wrestling and Jr Olympics at a very early age. The town that I grew up in has had a wrestling team for 70 or 80 years, and it seems like the entire town shows up at the dual meets.
The only sport that remotely approached the popularity of wrestling was football, and most of the wrestlers were on the football team primarily to stay in shape in the "off-season". There are hundreds of small towns like mine throughout Pennsylvania (and Ohio too).
Soccer was non-existent. Golf was a fun diversion. Basketballl was something to play in the driveway. We didn't have a hockey rink or an indoor swimming pool. Wrestling was something we looked forward to in the off-season (if we actually had an off-season), and we loved during the season. There is nothing like the heat of a practice room when it's zero degrees outside.
The vast majority of wrestlers are mat rats that you've never heard of - not everyone is a Kolat, a Schlatter, or a
Metcalf. But they love it just the same.
That's a long, wordy way of saying what RYou already said. Quality breeds quality, which establishes a tradition.