Mark Sullivan remembers running in the first Philadelphia Marathon in 1994, and the 1,500 or so people who showed up for it. It was a pretty large turnout for a race given the standards at the time, he recalled. Each year, he has seen it grow into what became an event that attracts tens of thousands.

Sullivan has returned every year since, and in the 23rd annual marathon this Sunday, he will be recognized as one of the event's "LEGacy Runners," a group of seven who have run in at least 15 of the 22 marathons. He is one of two runners who have been in every Philadelphia Marathon, with Bob Koen being the other. Both are the founding members of the LEGacy Runners program.

"We set it up as some way of acknowledging the runners who kept coming back," Sullivan said in a telephone interview.

Sullivan said the idea of the LEGacy runners started to form in the 15th marathon and took hold going into the 20th, when verification of returning runners was put into place. The marathon never kept track of runners before 2008, but Koen thought keeping records was a good idea, something he knew the Broad Street Run and the Philadelphia Distance Run (now the Rock and Roll Marathon) had done.

"After the [Philadelphia Marathon] started, I figured I could get a streak going," Koen said, remembering that he brought all his scores, medals, and shirts from past marathons to verify that he ran in them.

"There was no other way for them to tell," he joked.

Even as the years have gone by, Koen and Sullivan continue to look forward to the race.

"When you're running through the most historical city in the country, it's cool to see all the sites going by," Koen said.

"It's always a great race," Sullivan said. "And I'm looking forward to coming back and being a part of it."