The District of Columbia is a federal district, and its inhabitants are United States citizens, with all the rights and privileges of American citizens born or naturalized elsewhere. In my post today, I am only focusing on digital archives and databases that are related to the district itself, and not on national ones located within the district, such as the National Archives. I will leave those for my last post in this series, which will focus on national online archives and databases. Today's post also focuses on online archives and databases for U.S. territories. The territories' citizens have limited rights and you can read more about those here. According to Wikipedia, the following are inhabited unincorporated United States territories: American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands.
District of Columbia
District of Columbia Office of Tax Revenue Real Property Assessment and Sales Databases - http://otr.cfo.dc.gov/otr/cwp/view,a,1330,q,594345.asp - for researching ancestral homes
Historical Society of Washington, D.C. - http://www.historydc.org/Do_Research/collections.asp - while there aren't really online archives or databases on this site, there is an online catalog as well as finding aids. This is a great resource if you have DC ancestry.
Washington Research Library Consortium Digital and Special Collections - https://www.aladin.wrlc.org/dl/ - links to the digital and special collections of seven universities in Washington, D.C. comprising a treasure chest of photographs, documents, audio recordings, digitized newspapers, letters and much much more. The universities included are American University, Catholic University of American, Gallaudet University, George Mason University, George Washington University, Georgetown University, and the University of the District of Columbia. Fabulous collections!
American Samoa Historical Preservation Office - http://www.ashpo.org/ - history, newspaper articles, photographs and links to online maps
University of Guam's Micronesian Area Research Center - http://www.uog.edu/dynamicdata/MicroAreaResearchCenter.aspx?siteid=1&p=52 - this is the only website I could find for Guam, and currently there are no digital archives uploaded to this site, although I did find this message: "We strive to acquire, preserve and provide access to collections of archival maps, photographs, texts and cultural materials. This website will host much of our collections as we expand and dedicate staff time to digital resources."
Northern Mariana Islands
Northern Marianas College Library - http://www.nmcnet.edu/content.php?id=3 - no online archives or databases are available, but you can browse through the list of their collections and online catalog
Trust Territory of the Pacific Islands Photo Archives - http://libweb.hawaii.edu/digicoll/ttp/ttpi.html - in collaboration with the University of Hawai`i Library, these digitized photos showcase the Former Trust Territory, which included the Commonwealth of the Northern Marianas, The Federated States of Micronesia, The Republic of the Marshall Islands, and The Republic of Paulau. Follow the links on this page to be brought to the Trust Territory of the Pacific Islands Voyager Database as well.
Archivo General de Puerto Rico/General Archives of Puerto Rico - http://www.icp.gobierno.pr/agp/ - (in Spanish) scanned archives newsletters; sample photo, document, and audio files from the collections
Collectión Historia de Puerto Rico/The Ponce's Historical Archive & Historical Museum Digitalized - http://ponce.inter.edu/cai/connection_eng/index.html - digitized by the University of Illinois, this collection contains letters, documents, slavery censuses, photographs, maps, and other resources
El Archivo Histórico Arquidiocesano/Diocesan Archives of the Archdiocese of San Juan, Puerto Rico - http://www.preb.com/geneal/ahasjpr.htm - (in Spanish) while there really isn't archival material or databases online, there are some helpful genealogical information and links. Use Google to translate your pages.
Puerto Rico en breve/Puerto Rico in Brief - http://www.preb.com/ - (in Spanish) historical and genealogical links, census transcriptions, contact information for archives and parishes; appears to be a subscription website
University of the Virgin Islands Special Collections - http://www.uvi.edu/sites/uvi/Pages/Library-Special_Collections.aspx - includes funeral booklets, historical photographs, newspaper articles, research reports and occasional papers
Check out my District of Columbia Online Historical Directories and my District of Columbia Online Historical Newspapers pages.