Grandma's Marathon, the popular summer rite in Duluth, has sold out its June race — the fastest that has happened since 2016.

There are 9,500 runners signed up to tackle the 26.2-mile race June 22 along Lake Superior and the finish at Canal Park. The 2016 event reached capacity Dec. 31 and had 7,518 finishers, Grandma's largest-ever race.

The new sellout also is the fourth consecutive, according to race organizers. The Gary Bjorklund half-marathon is sold out, too, with 8,700 runners. The William A. Irvin 5K on June 21 has 2,700 in the field.

"Word-of-mouth marketing" after three years of good running weather, to an increase of people who took up running during the COVID pandemic are considered some of the factors, said Zach Schneider, the marathon's marketing and public relations director.

"We might also be seeing the natural evolution of those people who are now ready to take on an event like ours," Schneider said in an e-mail Friday to the Star Tribune. "If that is what's happening, our goal now is to provide a good experience to them this June and make them want to come back again."

Grandma's had record first-day registrations last October — the same day the Twin Cities Marathon canceled its event for the first time, owing to extreme weather heat.

With 6,690 finishers in the 2023 race, Grandma's became the 10th largest marathon in the United States. New York City Marathon is the largest (51,297 finishers).