Here are some links to resources on the history of lynching in the United States:

Essays in Modern American Poetry at www.english.uiuc.edu Three essays: "About Lynching", by Robert L. Zangrando; an untitled essay by John F. Callahan; and "Anti-lynching Campaign", by Dickson D. Bruce Jr.
In Motion: The Great Migration From the Schomburg Center for Research in Black Culture, a wonderful collection of primary and other resources on the Migration.
Two good articles on Wikipedia address The Nadir of Race Relations and Lynching in the United States.
And an article on Jim Crow Riots on nathanielturner.com.

The best site, of course, for all the historical documents connected with the Duluth lynchings has been created by the Minnesota Historical Society, The Duluth Lynchings Online Resource. This is the most complete collection of primary sources on any lynching in US History available to date. To download and read an analysis of the Urbanization of African-Americans in Minnesota, a project coordinated by UMD instructor David Beard and written by Elyse Dornhecker, Bridget Miller, and Michael Hughes, CLICK HERE. For a presentation on the sociological and historical dimensions of false accusations of rape, CLICK HERE. (Powerpoint)