Arizona’s lawmakers slipped Tuesday night a piece of legislation that would allow mining giants Rio Tinto and BHP Billiton to jointly build a massive copper mine in the state as part of a deal with the U.S. Government.

According to Arizona Republic the bill —set to be passed before the end of the year— would allow Rio to acquire 2,400 acres of the federally protected Tonto National Forest in southeast Arizona in exchange for 5,000 acres in parcels scattered around the state.

The land land-swap bill was added into the 1,600-page National Defense Authorization Act, the annual defense appropriation legislation that must be passed each year, according to the report.

Both miners have said they expect operations at their Resolution Copper project —55%-45% owned by Rio and BHP— to start as early as 2020. But they have had to deal with legal hurdles and opposition by the San Carlos Apache Tribe and other southwestern nations, who claim the massive project would weaken the ground beneath their sacred Native American lands.

Analysts are confident this time the miners will get their wish granted.

“This land swap has faced a long and bumpy road in Congress,” Caitlin Webber, a Bloomberg Intelligence analyst told The Daily Telegraph.

“Finally being tucked into this must-pass bill is the closest it’s been to enactment,” she added.

Resolution Copper, located in Arizona’s famous Copper Corridor, is expected to create 3,700 direct and indirect jobs and bring more than $6o billion in economic benefits to the state over its 66-year life. Rio and BHP estimate that output from the mine will meet 25% of the U.S. total demand, which will make it North America’s largest copper mine.

Learn more about the project: Resolution Copper Mining – Mine Plan of Operations from Resolution Copper on Vimeo – http://vimeo.com/91436060