If you have already activated your account DO NOT click the activation link again. Simply click Sign In in the upper left corner on PBS.org and begin browsing Passport content.
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If you do not see the blue Passport icon () next to your name, you have not completed the activation process or you have not signed in with the same email address you used when you activated your Passport member benefit. Think of any other email addresses you may have used and try signing in with those until you see the blue Passport icon next to your name.