The HGS is an Affiliated Society of the AAPG. That means that AAPG members that live or work in the HGS geographic area are assigned to the HGS as their Affiliated Society, whether or not they are a member of the HGS. Many are not HGS members. An AAPG member can also request to have an Affiliated Society that is not were they live or work, by request of that member.
The purpose of this is to assign Delegates to the AAPG membership for representation in the AAPG House of Delegates. A Delegate represents 70 members and votes in the House of Delegates at regular meetings. The Delegates are elected to the House by a vote of the AAPG members with that Affiliated Society, and that election is managed by the AAPG.
The HGS has nothing to do with the House of Delegates other than the fact that many of the elected AAPG Delegates are also HGS members.
The links below are provided for further information purposes: