Sky Schaudt/KJZZ

Traffic on Interstate 10 in Phoenix from the Loop 202 ramp on the Mini Stack in March 2019.

When we talk about traffic in the Valley we often refer to the "Stack" and the "Mini Stack." A listener used our Q&AZ submission form to find out what those terms mean and where in the Phoenix area they are.

KJZZ relies on Arizona Department of Transportation data to compile our traffic reports. They keep track of everything from rogue furniture on the freeway to crashes blocking the shoulder.

ADOT spokesman Doug Nintzel says while the term "stack" can refer to any location where freeway ramps are built one on top of the other, in the Valley it usually means one specific convergence.

"And that’s the I-10, I-17 interchange to the north west of the downtown Phoenix area near 19th Avenue and McDowell Road,” Nintzel said.

Nintzel says the Mini Stack is a reference to northeast of downtown at the interchange of the Interstate 10, State Route 51 and the Loop 202 Red Mountain Freeway.

Stacking ramps is a common feature around the country that allows major highways to merge.

This story came to us from listener Melinda Weisser-Lee through our reporting project Q&AZ.