The Kiwi, who has won the series six times, held off Graham Rahal to move into second position on the points table, 101 behind Alex Palou who finished seventh. There are three races remaining.
Dixon’s road course victory in the Gallagher GP was a case of "spin and win", after the Kiwi survived an accident on the opening lap.
Dixon - who started on the eighth row - set a new record just by lining up with it being his 319th consecutive race.
After the victory, the 43-year-old Dixon said it had been a "trying year".
"You always have doubts - that’s an unfortunate part of the business," he said, as he celebrated with his family.
It was the 54th victory in Dixon’s remarkable career, which places him second to the legendary AJ Foyt who had 67.
Rahal, who had claimed pole position, was in awe of Dixon’s record of 19 consecutive seasons with a victory.
"We were going up against the best of all time," he said of Dixon.
"(Dixon’s record) it’s insane, absolutely ridiculous."
Fellow New Zealander Scott McLaughlin finished eighth.
