Delta Air Lines is offering double miles on flights from Seattle to San Francisco, Los Angeles and Las Vegas until October 31 next year.
Skymiles members who register for the promotion by the end of this year will receive bonus miles on these routes.
Registered members may earn unlimited bonus miles on the Seattle flights during the promotion, provided travel is booked by December 31.
Members may begin or end their travel in any city to earn bonus miles on flights from Seattle to San Francisco, LA or Las Vegas.
Jeff Robertson, vice president of SkyMiles, said: "We're inviting SkyMiles members to celebrate one of Delta's fastest growing global cities by earning double miles on our newest Seattle routes.
"These new flights and expanded service allows Delta to enhance Seattle's presence and provide customers with another reason to experience Delta's award-winning product."
Delta last week announced that it has redesigned its BusinessElite meal service to give passengers more sleep time (see news, October 16).
Graham Smith