PBS
Wnet: Thirteen: Freedom: A History of Us: A War to End Slavery Webisode 6
A wonderful, interactive site covering many aspects of the Civil War. See photographs, primary sources, and find interesting tidbits about the war. Included are links to lesson plans, teacher guides, resources, activities, and tools.
Civil War Home
Home of the American Civil War: Border States in the Civil War
From "The Historical Times Encyclopedia of the Civil War" is this explanation of the critical importance of the border states and why the Lincoln administration worked to keep these states as part of the Union.