"What better place to spend this incredible weekend!" said Crow amid the magnificent natural rock formations of the Red Rocks Amphitheatre outside Denver.
Opening the concert, Crow performed, among other tunes, "God Bless This Mess."
In the first of several messages, Sugarland's Jennifer Nettles told the crowd: "Reach your hand out and pat yourself on the back for being such great people and caring about this environment."
Matthews, whose saxophonist LeRoi Moore died last week from injuries sustained in an all-terrain vehicle accident, admitted to being a man of few words – on stage, at least.
"Nice to be in a place where a lot of people are talking with a whole lot of sense," he said.
Virginia Gov. Tim Kaine introduced his home-state favorite, the Dave Matthews Band, and alluded to Moore's death. He said the band, just as Barack Obama did, will succeed in their uphill struggle.
"This has been a tough, tough week for these guys," said Kaine. "They will climb this."
Matt Sayles / AP