I grew up in Gaborone, Botswana. My parents are both infectious disease MD's and worked extensively with local clinics and hospitals on HIV/AIDS research. My personal statement reflected on the experiences of one particular AIDS infected patient of theirs who became incredibly close with our family, and who displayed tremendous courage in publicly announcing their positive HIV status despite the negative social connotations such a decision would leave in its wake. In summary, the statement was one that followed...

"Why Northwestern University"

With any "Why us" essay, it's important that you pick 2 or 3 central aspects of a school, and go in depth on them. Don't try to fit every detail of why you like a school into 2 sheets of paper, and sacrifice quality for volume. My defining traits that made NU stick out to me were it's strength of athletic conference (Big Ten sports, and all the excitement that comes with it) coupled with their academic reputation. Other topics I touched on...

Size of student body first....