What were the causes and effects of the Louisiana Purchase?

The essay should be two – three pages in length, in MLA format, double spaced, using 12 font only.  Students must use at least 3 reference source and not all can be from the internet (example, if you have three sources of references, one MUST be from either a book or other form NOT ALL INTERNET).  Also, serious college students should NEVER use or cite “Wikipedia.com,” so I will deduct points from the total if I see it cited or used.