American Geographical Society
The AGS is the oldest professional geographical organization in the U.S., founded in 1851. Their site includes information about the organization and membership.
Association of American Geographers
Since 1904, the AAG has served to advance professional studies in geography; it's the leading professional organization in the U.S. The site includes information about membership, the annual meeting, specialty groups, and more.
Canadian Association of Geographers
The home page of the Canadian Association of Geographers, publisher of The Canadian Geographer. Information about annual meetings, membership, publications, and more.
The Geographical Association is an association of nearly 10,000 members with a mission to further the teaching of geography and to communicate the value of learning geography for all.
International Geographical Union
There's not much to the International Geographical Union website, but it exists.
National Council for Geographic Education
The NCGE is quite active promoting geography in schools. Their site includes information about membership, activities, the annual meeting, and more.
Royal Geographical Society
The RGS merged with the Institute of British Geographers in 1995 to form a large society. Learn about the organization and membership at their site.