"We aren't sure how he got here. We do have some theories," said Angela Rudolph of the SPCA of Northern Nevada.
Bobby's owner, Kyle Preston of Great Falls, told SPCA there's a railroad track across from his house. He suspects Bobby might have somehow hopped onto a train and came all the way to Nevada.
Bobby disappeared a year and a half ago, Preston told the SPCA.
The Prestons never stopped looking for Bobby, continuing to leave special cat food outside to attract him, Rudolph said.
"They posted on social media and contacted local shelters. They never gave up hope, which is incredible."
A Preston family friend, who works for Delta Air Lines, picked him up Friday and flew him back to Montana from Reno-Tahoe International Airport.
What Bobby was up to all this time will probably remain a mystery.
"Bobby's probably going to keep that to himself," Rudolph said.