Carlos Munoz secured his fourth pole position of the Firestone Indy Lights season after going fastest in Iowa qualifying.
Munoz was the fifth driver to post a time and went to the top with a two-lap average of 157.457mph, beating the previous benchmark set by Zach Veach.
"I knew we had a great car," said Munoz. "We worked really hard and we had a really good car in those two laps. But the race is what's important, and that's what we have to focus on."
Jack Hawksworth rebounded from a string of difficult weekends to bump Veach off the outside of the front row with a 158.794mph average, although Veach's 158.742mph effort was good enough for the Andretti driver to hold on to third.
The big surprise of the session was Indianapolis winner Peter Dempsey, who will start from the rear of the eight-car grid after getting loose on the exit of Turn 4 on his first flying lap.
Pos Driver Team Speed
1. Carlos Munoz Andretti 157.838
2. Jack Hawksworth Schmidt 157.947
3. Zach Veach Andretti 157.198
4. Jorge Goncalvez Belardi 157.713
5. Sage Karam Schmidt 157.949
6. Gabby Chaves Schmidt 159.457
7. Juan Pablo Garcia Moore 158.794
8. Peter Dempsey Belardi 158.742
Format: Average speed of two-lap run