Lewis and Clark County's Motor Vehicle Department in Helena temporarily closed Thursday after receiving an envelope containing white powder.
The office reopened Thursday afternoon, after officials determined the substance was not hazardous.
The envelope arrived late Wednesday afternoon. A Helena Fire Department HazMat team was called to handle the package, which was sent to the Montana State Health Lab for testing.
"While the results don't definitively tell us what the substance is, they do confirm that it is not hazardous," county spokeswoman Jeni Garcin said in a Thursday press release.
Helena Police Department Capt. Curt Stinson said the package came from another government office, and "they were expecting to get it." He said the package was in the office "a little while," but employees were surprised to find the white powder inside, prompting a call to police.
"There were no injuries, no symptoms" of sickness, Stinson said.