[3] On August 27, 2020, another was added, as Alexander Hughes shot a 55 in Jenks, Oklahoma, within 100 miles of where Gibson had his best day.
[4] Possibly the lowest documented round in competitive golf is 57, achieved by (among others) Bobby Wyatt in the 2010 Alabama Boys Junior Championship, and Alex Ross in the 2019 Dogwood Invitational.
Ross's round was 15-under-par for the Druid Hills Golf Club course in Atlanta, and included 13 birdies and one eagle.
Greg Norman, Vijay Singh, Brooks Koepka and Tommy Fleetwood are the only golfers to record two rounds of 63 in the majors.
In women's major championships the lowest round is 61, which has been recorded by three golfers: Leona Maguire, Lee Jeong-eun and Kim Hyo-joo.