Following is a list of excellent websites for additional research.
For an understanding of the period of legal slavery in New York State, go to http://www.slaveryinnewyork.org, the website of the first New-York Historical Society exhibition on this topic. The website can also be reached via the Society's website, http://www.nyhistory.org.
Two online exhibits, available at the Library of Congress website, provide source documents and explanatory text on a wide range of topics. Go to http://www.loc.gov/exhibits and select either "The African American Mosaic: African American Culture and History" or "The African American Odyssey: A Quest for Full Citizenship."
The New York State Department of Education website offers an extensive documents-based curriculum focused on the history of slavery in New York State. "New York and Slavery: Complicity and Resistance" is at http://www.nyscss.org/resources/publications/NYandSlavery.cfm.