Seattle-Tacoma International Airport to Portland International Airport is one of the more heavily trafficked routes in the United States. 
Alaska Airlines and 
Delta Air Lines offer numerous daily direct flights between the two centers using three aircraft types and eight variants. Seattle is the busiest destination from Oregon’s Portland with 8,588 annual flights (followed by Los Angeles with 4,571 annual flights). According to data provided by Cirium (an aviation analytics company), these are the types of aircraft to be flown between Seattle and Portland.