Here is a useful set of history teaching resources from the National Humanities Center. Toolbox Library: Primary Resources in U.S. History and Literature, is a set of teaching units for American history, with framing questions, printable primary sources for classroom use (not only written sources but historic images as well), discussion questions, and supplemental sites.
The printable PDF handouts are beautifully done! See for example Maroons and free blacks, 1600s, three documents, which includes compelling primary source documents nicely formatted with period illustrations in color. This is accompanied by three other handouts--black codes from Haiti and Cuba and some period illustrations of slaves in the Caribbean.
There are seven units online so far with topics ranging from Becoming American: The British Atlantic Colonies, 1690-1763 to The Triumph of Nationalism/The House Dividing: America, 1815-1850 to The Gilded and the Gritty: America, 1870-1912.