U.S. National Archives Guide for Genealogists and Family Historians

The U.S. National Archives has over 2 million digital copies available. However, to get some perspective, the Archives lists its holdings as follows:

• 10 billion pages of textual records
• 12 million maps, charts, and architectural and engineering drawings
• 25 million still photographs and graphics
• 24 million aerial photographs
• 300,000 reels of motion picture film
• 400,000 video and sound recordings

If you are not familiar with how the National Archives works, there is an online Guide for Genealogists and Family Historians directed at the Archives Online Catalog. There is also an section dedicated to genealogists. Here is a screenshot of the Resources for Genealogists page:

The National Archives has its own YouTube channel called appropriately, U.S. National Archives. Looking at the number of views of these presentations, it appears that these online resources are relatively unknown. Here is a screenshot of the YouTube channel:

 

In addition, the National Archives held a Genealogy Fair on September 3 &4, 2013. Recordings from the Fair are online at the National Archives Virtual Genealogy Fair website. This is an annual event. 

You may also want to view the Online Research Tools and Aids webpage. Don't get the impression that there are actually records online. The "online" portion of the records consists mainly of catalogs. The National Archives relies mostly on Ancestry.com to provide some of its record collections.