My mothers family has had a farm in Western PA for over 200 years. They get natural gas, oil and helium out of it. It wasn't until the 90's where a new company from Texas really wanted it and the royalties were enough that my parents retired at 60 and 61, the farm is partially owned by 20 people who also have kids and grandkids. When my parents pass away, my brother and I could probably live off of the royalties for the farm, not an extravagant lifestyle, I think my mother gets a little over 30k a year, but royalties in Western, PA are no joke. I have also heard New York farms are getting a ton of royalties from the same deposit, I forget the name now, but in the early 20th century there were a ton of oil companies around Pittsburgh.