Once the B.A.A. decided to invite back the runners who were stopped on the course, another full wave made sense.
"If the field size were to remain at 27,000, then we'd have to take 5,000 slots away from largely qualified runners, and some charity runners or something, which we didn't want to do," Grilk said. "People work so hard to qualify for this you'd hate to say, 'No, this year of all years, you can't come do it because we're bringing back some other people.'"
After expanding to 38,000 in 1996, the marathon returned to about 10,000 the next year. It continued to grow until hitting the number of around 27,000 that the B.A.A. and the towns found manageable.
Although the race is expected to return to that size next year, Grilk said no decisions have been made.
"We never specifically limited it and said, 'And then we will go back to exactly what happened before,'" he said. "After this year is over, then we'll do what we do every year: have another set of conversations with everybody and listen."