How and why did slavery grow in North America?

How and why did slavery grow in North America? Why did slavery expand in the south while it diminished in the North? What laws did the government make regarding slavery, and to what purpose? Is slavery mentioned in the Constitution?

This paper should be in size 12 font, Times New Roman, and double spaced, with 1 inch margins. Citations should be done using chicago style.
Using the proper format is worth 10% of your grade. there must also be a clear thesis, and all main points must support that thesis.

You must include a bibliography at the end of your assignment.