DENVER (KDVR) — Presidential candidates are spending millions of dollars in Colorado and giving the economy a big boost.

In February alone, at least six candidates are making public appearances in Colorado and in the process, are pouring millions of dollars into the Centennial State.

“We are a swing state and getting more votes in Colorado is very important for both parties and all candidates,” said Metropolitan State University of Denver economics professor Dr. Kishore Kulkarni.

The campaign visits and spending started months ago. For example, in August, Sen. Kamala Harris spent nearly $2,200 to hold a rally at a high school gym in Denver.

Since then, the rallies and spending have only increased. Last weekend, Sen. Bernie Sanders spent thousands to pack more than 11,000 people into the Colorado Convention Center for a rally. The Convention Center declined to say exactly how much money the Sanders campaign paid for the event.

“When you’re a targeted battleground state like Colorado, it means you’re hiring local. It means you’re contracting with local caterers, local printers and it means you’re renting office space,” said Colorado Democratic Party Chair Morgan Carroll.

Former Mayor Mike Bloomberg has an office downtown that reportedly has more than 40 staffers. Plus, he’s spent millions on ads in Colorado.

“If your (primary is) earlier, candidates spend more,” Kulkarni said.

And it’s not just Democratic candidates.

President Donald Trump is set to hold a big rally at the Broadmoor World Arena in Colorado Springs alongside Sen. Cory Gardner on Thursday. As of Wednesday night, hundreds of people were already lining up for it.

The Trump Victory Committee would not say how many people it employs in Colorado, but has spent hundreds of thousands of dollars and has offices in multiple cities, including Denver, Grand Junction and Pueblo.

A committee spokesperson said it’s the largest presence ever for a Republican presidential candidate in Colorado at this stage of the campaign.