Creating the American Nation is another guide with 17th and 18th century online primary source collections. There is some duplication with this guide.
The organization for this page and most links were borrowed from "History: American: Primary Sources 17th & 18th c." created by the University of Washington Libraries.
When searching a database of books (think: OneSearch, Google Books, or WorldCat):
Also, look for Library of Congress Subject Headings with those terms. For example:
United States -- History -- Sources
United States -- History -- 18th century -- Sources
