Here is a link to the web site http://www.pbs.org/wgbh/aia/part4/4p2932.html.
You have to see the incredible work done by Dean Eastman and other teachers and students from Beverly High School in Massachusetts on the www.primaryresearch.org website. In particular, check out the section entitled, “African-Americans in Antebellum Boston,” (www.primaryresearch.org/bh). They have pulled together an amazing amount of primary resource material, including page images and tables relating to the Boston Vigilance Committee records which was the area’s principal Underground Railroad network. See especially the account books of Treasurer Francis Jackson –amazing! All of this material is filed under Records of Voluntary Associations. There’s also lots more including GIS maps, census records, full-text documents, legislative reports and all kinds of tools for researching the black community in nineteenth-century Massachusetts, especially around Boston. Highly recommended!