The National Park Service returns 10 dollars for every dollar of taxpayer investment, not only collecting admission and camping fees, but filling surrounding hotels and restaurants while emptying the shelves of local grocery stores and sporting goods outfitters.
The profitability of the NPS was most ironically demonstrated last October during the 16 days of the federal shutdown, when 7.88 million visitors stayed home because the parks were closed. Even that short period cost $414 million in lost revenue: All the entrance passes visitors would have bought, all the hotel rooms and bed and breakfast nooks where they would have stayed, all the meals they would have purchased in communities surrounding the parks, and all the walking sticks and picnic baskets and hiking boots they would have bought for their adventures.