Could it be a tree frog?

I am pretty knowledgeable on the local frog and toad calls here, so I think I can rule that out. I think it's an insect of some sort, just trying to figure out which one.

for years i was told this was treefrog. i have now been told that describes tree crickets, though i cannot find the exact match. there are so many.

It sounds like it is probably cicadas. They are insects that live in the tops of trees and call in late summer. The call comes from vibrations of certain structures (tymbals) on their outer body covering (exoskeleton). The muscle inside the tymbal relaxes and contracts, producing a clicking noise which is their mating call.