Are you referring to the proposed Red Rock yard in Pinal County, Arizona?
It was to be up to 1500 acres (sixth largest in US) located along I-10 north of Tucson near Picacho Peak, site of a Civil War battle, current state pack, and tourist trap of an ostrich farm monster truck ride. The county denied the request in June 2019 to rezone the land, but another vote was to be held later in 2019 that I don't recall hearing the outcome. The Pinal County website has a page dedicated to the project.
UP Red Rock Yard