But those against the project, who also stood out in orange T-shirts, completely disagree.
"It really is not going to improve the economy of Temecula and this area; it will put people out of work," said Temecula resident Sylvia Garcia.
Opponents also said the quarry would drive tourists and residents away.
"Actually, if it's approved, we're probably going to move," said Rainbow resident Carl Matthews.
Some are so staunchly opposed to the quarry that they will be urging people to stay away because of health concerns if it opens.
"I would never encourage anyone to come to a town that has any granite quarries in it," said Rainbow resident Marilee Ragland.
But supporters think those arguments are just scare tactics.
"There are quarries in Corona, there are quarries in Indio, and there are no problems around those quarries," said Hemet resident Alan Richardson.
Still, opponents point out that many of the quarry's supporters don't have to worry about the consequences because they don't even live near the site.
Patrick McCorde was one such supporter who came out from Santa Ana. Although he is not a Riverside resident, he said he had more than enough reason to be there.
"Whenever there's another union, that's part of our family, so we're here to support them," said McCorde. "It does impact us personally, because the reason being that it impacts us personally is we're looking for allowing more work for more people."
And that's No. 1 argument almost every supporter makes - the need for more jobs.
"I just support jobs, and I believe that we should bring jobs to the riverside community, and that's my biggest reason for supporting liberty quarry," said Riverside resident Andy Menjivar.
It's still anybody's guess which way the vote will go. At least two of the supervisors have asked extremely critical questions about the project, while the other three have been less inclined to speak up.