http://www.nps.gov/history  The National Register of Historic Places is the Nation's official list of cultural resources worthy of preservation. It is part of a national program to coordinate and support public and private efforts to identify, evaluate, and protect our historic and archeological resources.

http://www.nps.gov/history/hps/tps  Technical Preservation Services provides the tools and information necessary to take effective measures to protect and preserve historic buildings.
 
http://www.ncptt.nps.gov  National Center for Preservation Technology and Training (NCPTT)

http://www.oregonheritage.org  The State Historic Preservation Office – National Register
Program – Tax Incentives – Survey and Inventory.

http://www.salemhistory.org  Salem History Project

http://photos.salemhistory.net  Salem Library historic photos page

http://www.oldhousejournal.com  Various articles on historic house rehabilitation, insurance providers, resources and historic preservation information.

http://www.preservationnation.org   The National Trust for Historic Preservation is a private, nonprofit membership organization dedicated to saving historic places and revitalizing America's communities. 

http://salemquarterly.com  Salem Historical Quarterly contains articles and blogs regarding Salem history and attractions.