The U.S. Forest Service says about 9,700 members of the Rainbow Family have shown up for their annual gathering in southwest Montana.

That makes the remote camping site about 10 miles southwest of Jackson in the Beaverhead-Deer Lodge National Forest the eighth largest community in Montana.

Nearly 2,000 vehicles are in the area, creating traffic congestion and dust. Beaverhead County officials say the population surge is straining some services, especially law enforcement and healthcare facilities.

The gathering is expected to last through Sunday, July 7. Family members went silent from midnight until noon on July 4 as part of their prayer for world peace.

The Rainbow Family reportedly originated during the Vortex Gathering in Canby, Ore., on Aug. 28 to Sept. 3, 1970. Two people who attended the Vortex Gathering, Barry “Plunker” Adams and Garrick Beck, are considered among the Rainbow Family elders, or “high holies”. The group has no official leaders.

Gatherings typically last for a week, often focusing in the U.S. on the Fourth of July, when family members pray, meditate or observe silence to focus on World Peace. The group’s full name is Rainbow Family of Living Light.