There are
3,040 mi
from Somerville, MA to Seatac, WA
That's the driving distance. It would take 2 days 6 hours to go from Somerville, Massachusetts to Seatac, Washington.
The flight distance (direct flight from Somerville, MA to Seatac, WA) is 2,484.41 mi.
3,040 mi = 4.83 kms