WASHINGTON  The Marine Corps Marathon here bills itself as “the people’s marathon.” As the largest marathon in the world that does not offer prize money, it expects a field of 30,000 runners for this year’s race, on Oct. 31.

But apparently the inclusive spirit does not extend to the portable toilets.

Runners in the marathon and participants in rallies organized by Jon Stewart and Stephen Colbert will share the Mall on the Halloween weekend. On back-to-back days, they will take to the same streets, walk on the same lawn and enjoy the same scenery, with the Capitol as the backdrop.

But Rick Nealis, race director for the marathon, said that on Oct. 30 he would put metal padlocks on about 100 portable toilets he was setting up around the Mall for the race day, when the marathoners will be joined by an additional 10,000 runners in a 10-kilometer race.

Organizers for the simultaneous rallies on Oct. 30, which will have Comedy Central personalities as hosts, asked Mr. Nealis to share the toilets, promising to contribute to the cost and have them cleaned before the marathon’s start at 8 a.m. the next day. (The rallies officially end at 3 p.m.)