Regardless of the laws... if you want to drive slow, for the love of God, please stay in the right-hand lane on the interstate. And if you're jamming up traffic on a two-lane PULLOVER. Literally, everyone thanks you.
Interstate 90 was a parking lot. Traffic came to a complete stand-still many times due to crashes, pile ups, and slide offs. US 93 had dozens of it's own accidents. Montana is having a very rough week on the roads.
Snow, ice and wind have been a disaster for Montana road conditions since Wednesday morning. The entire state has been affected by harsh driving conditions and the first responders have been VERY busy.