San Diego has numerous organizations focussed on preserving the history of the County and educating the public about the rich history of our region. Below are some links that may be interesting to check out.
San Diego History Center (previously known as the San Diego Historical Society):
http://www.sandiegohistory.org
Save Our Heritage Organisation (SOHO):
San Diego Electric Railway Association:
Pacific Southwest Railway Museum
San Diego Police Historical Association
http://www.sdpolicemuseum.com/index.html
Ocean Beach Historical Society:
http://obhistory.wordpress.com
Lakeside Historical Society