More than 6,500 tickets have been sold for the benefit concert featuring musicians Neil Young and Willie Nelson, bringing in money for groups that oppose the Keystone XL pipeline.
One of the groups behind the anti-Keystone push, Bold Nebraska, said it plans to sell only 500 more tickets for the concert, which will be held on a farm in Nebraska.
The groups argue that the controversial oil sands pipeline would exacerbate greenhouse gas emissions, harm aquifers and threaten nearby farmland.
Young said he wanted to perform at the concert because Keystone "is a large step in the wrong direction for the health of the Earth."
"In a time when the ravages of Climate Change are evident, thoughtful people are realizing we are at the beginning of the end of the fossil fuel age," Young said in a statement. "For our grandchildren's survival we must begin to live differently."
The State Department is currently waiting for litigation surrounding the pipeline's route to be settled in Nebraska before resuming its national determination review.
Proponents of the pipeline argue Keystone would have little effect on the climate change, pointing to findings in the State Department's final environmental review.