All the local small airports in the USA sell 100LL – “One hundred, low lead”.

Modern small plane engines can run off regular unleaded, but a lot of small planes in the air are “old” and require leaded gas.

Piston driven planes still do use leaded gasoline. There is a very recent push to certify lead free avgas and progress is being made but they’re being a bit opaque and seemingly rushing it which is making a lot of people weary of it.

Planes that would land here typically use 100LL which contains lead. (LL stands for Low Lead). It’s not banned for aviation use.

There has been a push recently to use alternatives which don’t contain lead but most places still have 100LL as it’s a very long process to get things certified for aviation use.