The following exert is an eye witness statement. Please read into it what you will. This has been reported to mufon who I am sure are investigating:
I was returning from work, i drive a limousine,wile looking at the skyline of butte mt traveling at 70mph on i90 heading south i saw a dark gray ball above my car just off the drivers window,it was about 2000 or 3000 feet, i could tell the height because i was in a high altitude area and object was cutting the clouds. it was slowly pasding me.It stayed above me for about 60 miles till i arrived in missoula mt,it changed directions and started heading over missoula swish toward florence mt,im in a very long car,i tried to keep up with it through town,it seemed to slow over missoula then started to go up deep into clouds,i parked at a bank to get out and find it again to take photos,spotted it coming back down out of clouds, i took 33 photos from my 5mg phone wile stabilizing on car. 6 photos came out great.Wile standing and looking this thing was big and high, changed directions many times before getting out of view.