Namely the parks service and forest service. Pick the area you want to go first of course. They have tons of resources and niche info. Iβm planning a 2 week backpack through part of the John Muir trail and when I needed info I wrote an, in retrospect, rambling email to the parks serviceβs address. They got back to me in 3 days with a numbered list answering all my questions. Whoever answered was super helpful and understanding of even some of the sillier questions.
