Big Sandy is a town in Chouteau County, Montana, United States. The population was 605 at the 2020 census. The Lewis and Clark Trail, following U.S. Route 87, goes through Big Sandy. Big Sandy native Jeff Ament, Pearl Jam bassist, built the town a skatepark with his Montana Pool Service non-profit organization in 2010. Big Bud 747, claimed to be the largest farm tractor in the world, was located here from 1997 until 2009, and returned in 2020.