Across the roughly 85-million-acre National Park System there are, in theory at least, some 70 million acres envisioned as official wilderness. Forty-four million acres have received Congressional blessing as such, while another 26 million acres are in something akin to administrative limbo.
Some of those 26 million acres -- including roughly two-thirds of Big Bend National Park -- have been recommended for official wilderness designation...and seen that recommendation languish. There's an effort to turn roughly two-thirds of Big Bend National Park into Congressionally approved wilderness.
National Parks Traveler Podcast