There are a number of quality research-oriented websites available that may assist in locating information about United States history. In addition to the general history web sites listed under the web sites tab, the following may be of interest.
American Memory provides free and open access to written and spoken words, sound recordings, still and moving images, prints, maps, and sheet music that document the American experience.
An extensive listing of annotated websites dealing with all aspects of U.S. history. Note subsections on Colonial Period, Native Americans, Pilgrims, etc.
Making of America is a digital library of primary sources in American social history from the antebellum period through reconstruction. Browsable by subject or searchable by keyword.
A free online textbook authored by historians and sponsored by the Independance Hall Association of Philadelphia. It is organized chronologically with links to text and other suggested readings throughout.