Flight Tacoma International Airport departs from Seattle Tacoma International Airport at 10:02 and arrives at Missoula Missoula Montana Airport at 12:27.
The flighttime is about 23h 25m. The distance travelled ("as the bird flies"): 914 Km. So the average speed is roughly 39 Km.
There is an 3 hour time difference between Seattle and Missoula