McLaughlin lapped the 11-turn, 2.1-mile temporary street course with a best lap of 1m14.6099s, and will start ahead of Pato O’Ward (Arrow McLaren) and Colton Herta (Andretti).
Qualifying was delayed by over three and a half hours due to track conditions after heavy rain caused standing water when it was originally slated to run. As a consequence, it ran in dry and sunny weather instead.
Fast Six qualifying
O’Ward set the early pace at 1m15.3506s, before series leader Alex Palou (Chip Ganassi Racing) – who opted for new harder primary tres as opposed to used alternates – grabbed P1 with 1m15.2462s.
Herta beat them both with 1m15.2416s, but McLaughlin unleashed 1m14.6099s in the final minute to take pole.
O’Ward beat Herta for P2, but was 0.3296s slower than McLaughlin. That trio will start ahead of Palou, David Malukas (Dale Coyne Racing) and Romain Grosjean (Andretti).
Herta was angry with Grosjean’s team for sending his car out right in front of him, which he felt hampered his bid for the front row.
Top 12 qualifying
In the second round of qualifying, O’Ward set the fastest time of 1m14.5944s from Herta, Palou, McLaughlin, Grosjean and Malukas.
Failing to make it through were Will Power (Penske), Kyle Kirkwood (Andretti), hometown hero and title contender Josef Newgarden (Penske), Alexander Rossi (McLaren), series debutant Linus Lundqvist (Meyer Shank Racing) and Scott Dixon (Ganassi) who crashed hard at Turn 11 in the closing moments and will start 12th.
Group stage qualifying
In Group 1, McLaughlin was fastest with a time of 1m15.1629s, half a second ahead of Dixon, Malukas, Rossi, Newgarden and Lundqvist.
Missing out were Toronto winner Christian Lundgaard (Rahal Letterman Lanigan Racing, who failed to progress by 0.0093s), his team-mate Graham Rahal, Helio Castroneves (MSR), Rinus VeeKay (Ed Carpenter Racing), Santino Ferrucci (AJ Foyt Racing), Agustin Canapino (Juncos Hollinger Racing, who lost a lap for a pitlane violation) and Benjamin Pedersen (Foyt) – who caused an early red flag by overshooting Turn 11 and stalled.
In Group 2, Herta set the quickest time at 1m15.0030s, 0.05s ahead of Kirkwood, Palou, O’Ward, Grosjean and Power, who got away with a wall brush.
Making no further progress were Felix Rosenqvist (McLaren, knocked out by 0.0039s), Marcus Armstrong (CGR), Callum Ilott (JHR), inaugural winner here Marcus Ericsson (CGR), Jack Harvey (Rahal), Sting Ray Robb (Coyne), Devlin DeFrancesco (Andretti) and Ryan Hunter-Reay (ECR).