To get you into the habit of using WorldPerks hotel and car rental partners and remembering to collect the miles, Northwest will double all base miles that you receive from any hotel or car partner (starting with your second transaction) between March 1 and May 31. That’s right — any of those partners.

Register online at http://www.nwa.com, then simply provide your WorldPerks number at time of hotel check-in or car rental pick-up.