Joseph Thomas Hansen (pictured), of Claire City, was arrested Aug. 23 after someone tipped off a police school resource officer that Hansen had talked about an attack, authorities said.
Clair City is a small town between Sisseton, South Dakota and the North Dakota state line.
He has pleaded not guilty to selling, transporting or possessing an explosive device and possessing substances with the intent to make a destructive device, and is due back in court Sept. 14. If convicted of all charges, he could face up to 25 years in prison.
He listed 39 people he hated and the reasons why, and he researched the 1999 Columbine school massacre in Littleton, Colo., in which two student gunmen killed 12 classmates and a teacher and wounded 26 others before committing suicide.