One of the most popular events of the PGA Tour returns to Scottsdale this week. The first round of The Waste Management Phoenix Open kicks off Thursday, but golf fans have been trickling in all week.

Tens of thousands of people are expected to attend each day. Researchers at ASU found the tournament brings about $400 million to Arizona’s economy each year.

Expect heavy traffic in Scottsdale, on the Loop 101 and near the course at Bell and Hayden Roads.