American Historical Association
http://www.theaha.org/
"The American Historical Association (AHA) is a nonprofit membership organization founded in 1884 and incorporated by Congress in 1889 for the promotion of historical studies, the collection and preservation of historical documents and artifacts, and the dissemination of historical research. “

National Center for History in the Schools
http://www.sscnet.ucla.edu/nchs/
"The National Center for History in the Schools has published over sixty teaching units that are the fruits of collaborations between history professors and experienced teachers of both United States and World History. The units represent specific issues and dramatic episodes in history from which you and your students can pause to delve into the deeper meanings of these selected landmark events and explore their wider context in the great historical narrative. “

National Council for History Education
http://www.history.org/nche/
"The National Council for History Education is a non-profit corporation whose Board of Trustees is dedicated to promoting the importance of history in schools and in society. NCHE links history in the schools with many activities sponsored by state and local organizations. “

National Council for the Social Studies
http://www.ncss.org/
"Founded in 1921, National Council for the Social Studies has grown to be the largest association in the country devoted solely to social studies education. With members in all 50 states, the District of Columbia, and 69 foreign countries, NCSS serves as an umbrella organization for elementary, secondary, and college teachers of history, geography, economics, political science, sociology, psychology, anthropology, and law-related education. “

National Park Service History: Ask a Question
http://www.cr.nps.gov/history/askhist.htm
“Do you have a question about the national parks, the National Park Service or American history? Ask one of our historians listed below. Just click on the name of the person you want to contact and send your question by e-mail.”
Over one hundred National Park Service employees with either M.A.’s or Ph.D.’s in history are here willing to answer your questions about U.S. History. Their specialties are listed so that you can send you question to a historian specializing in that field. Obviously, they are ready to answer questions about the National Parks, but are also willing to answer general U.S. History questions also. Sometimes probing the mind of a historian can produce new perspectives, approaches and methods for teaching history as well as ideas for sources and related topics. Make sure to use the “Selected Subject Specialty Index,” or “State” index to choose to whom you should direct your question. (BR)

Organization of American Historians
http://www.oah.org/
"The Organization of American Historians is the largest learned society devoted to the study of American history. Since its founding in 1907 as the Mississippi Valley Historical Association, the OAH has promoted the study and teaching of the American past through its many activities. The work of the organization is supported primarily through the contributions of its membership.”

Society for History Education
http://www.csulb.edu/~histeach/
"To support faculty devoted to the importance of history education in universities, community colleges, and pre-collegiate schools.”

Western History Association
http://www.unm.edu/~wha/
Western History Association exists to promote the study of the North American West in all its varied aspects and in its broadest sense. The WHA was founded in 1961.”
For secondary teachers with a special interest in the history of the U.S. West, this organization is perfect. They hold an annual conference and publish Western Historical Quarterly.