Isn't it immensely difficult to restart an aluminum smelter? Also, my vague memory of these is that in North America most of them are in areas with abundant hydro power.
(citations needed.... I'm recalling this from a story someone told me ~15 years ago about the Alcoa plant in Victoria, Australia)
The waves of Enron took out most of them decades ago when its destruction rolled through the energy markets. IIRC, the last NW aluminum smelter closed a few years ago.