Join through this link (be sure to add EAS to your section memberships): https://secure.aaanet.org/form_mbr/index.cfm.

Go to http://www.aaanet.org/mbrprnt.pdf and print out the "pdf" page. Where it requests your AAA membership selection, indicate that you are already a current AAA member. Find the section you wish to add. Mark the appropriate section and type of membership (ie full member,
student, etc.) You can pay by check (send it with this form and your name/address info) or you can fax the form back to 1(703)528-3546 if using Visa/Mastercard. Unfortunately, the interactive membership e-commerce form can't handle joining only a section.

The AAA mailing address is:
AAA
2200 Wilson Blvd Ste 600
Arlington VA 22201-3357