A resource providing documents in US History from the 1600s to present day. The overwhelming majority of these primary sources are presidential speeches/inaugural adresses and famous supreme court cases.
I have used this link in one of my classes at the University.
It includes documentation of every slave voyage (from where it left and where it was headed), how many slaves were on the voyage, and from where they were from.
It contains maps, graphs, etc., and is very interactive.