Patrol spokesman Bill Brooks says the bus pulled into the Sierra Blanca, Texas, checkpoint about 9 a.m. Friday. Brooks says an officer smelled pot when a door was opened and a search turned up marijuana.
Brooks says the Hudspeth County sheriff was contacted and Nelson was among three people arrested.
Sheriff Arvin West didn't immediately return a phone message left at his home Friday, but he told the El Paso Times that Nelson claimed the marijuana was his. The singer was held briefly a $2,500 bond before being released.
Nelson spokeswoman Elaine Schock declined to comment when contacted via e-mail by The Associated Press.