At an age some runners are slowing down, Burt Carlson was just getting started.

Carlson ran his first marathon at 57. Over the next 30 years, he averaged 10 marathons a year. He also ran numerous ultramarathons — races of up to 100 kilometers (62.1 miles) in distance — and competed in 50-mile road races and 24-hour races.

In all, Carlson ran 324 marathons and ultramarathons. He ran in nearly 100 marathons after his 81st birthday.

“Minnesota has a long, rich history of long-distance runners,” said Minnesota native Carrie Tollefson, a 13-time state high school champion, five-time NCAA champion and an Olympian in 2004. “Burt was very extraordinary.

“I last saw him at the Reggae Marathon in Jamaica in 2010. He was 85 and ran the half-marathon. It was all about the run for him. He brought joy and love to the running community with the stories he’d tell. He’d keep people alive.”

Carlson, of Mound, died on March 10. He was 94.

Tollefson said it was always fun to hear him talk. “His story resonated with people because he was older when he took up running,” she said.

Carlson was born in Minneapolis on Sept. 26, 1925, to Bennett and Myrtle Carlson. He was raised in Minneapolis and attended Minneapolis Central High School. He graduated from the University of Minnesota with a degree in mechanical engineering.

He went to work for 3M Co., designing facilities for many of the company’s plants. He retired in 1990.

In retirement, running took him all over the world. He ran in all 50 states and in nine countries on seven continents.

In 1989, he competed for Team Minnesota in the World Masters Games in Denmark. He earned medals in the triathlon and steeplechase and ran in the marathon and the 10,000-meter race.

In 1990, at the age of 65, he became the oldest Minnesotan to run in the Edmund Fitzgerald 100-kilometer world championship race along Minnesota’s North Shore.

In 1997, he was the oldest entrant to compete in the 50-mile Le Grizz ultramarathon in Montana. It was a homecoming for Carlson.

From 1949 to 1951, he worked on the construction of the nearby Hungry Horse Dam. He ran the entire race wearing the same aluminum hard hat that he wore while working on the dam.

In his 80s, he was routinely the oldest finisher at a marathon. In 2003, the American Lung Association Running Club recognized him as a “Minnesota Running Legend.”

In 2006, he was the only runner over 80 to finish the Twin Cities Marathon. That year he was named his age-group runner of the year by the Minnesota Distance Running Association.

In 2006 and 2007, he was the oldest finisher in Grandma’s Marathon, from Two Harbors to Duluth. In his early 90s, he was still running a half-dozen races per year.

“Running is not a sport for everyone,” said Tollefson. “It’s not easy. He wasn’t quite as fluid at 85 years old, but he was still showing up and that’s a compliment. He was still bouncing off the starting line. He was awesome.”

He continued to speak to running groups, including high school cross-country teams, into his 90s.

“You could tell kids loved hearing from him,” Tollefson said.

Carlson is survived by his son, Robert Carlson, grandson Craig Carlson and granddaughter Tanya Carlson. A memorial service will be held at a later date.