I’m from NYC, and I was wondering if it was an over-represented area, and if so, would it have a large effect on my BS admissions? Or are the over-represented areas more in New England?
Yes.
Whether it will have a “large” impact depends on the strength of your application. Nobody can give a more definitive answer outside the admissions office.
@skieurope I’ve heard some stereotypes about NYC kids, like they’re spoiled or annoying, are those pervasive?
The stereotypes or the reality?
The stereotypes are real. In reality, some are, some aren’t. Just like privileged kids from any region.
@skieurope The stereotypes. I meant if people would assume things about me.
Generally not on the first meeting, unless you roll up in a Bentley, and the chauffeur and butler help you move in. 
@4everstressed: Admissions officers read all applications, recommendations & other submitted material. Your application will create an impression of you so please avoid stressing out about stereotypes or other factors not within your control.
Honestly it really depends. A kid who lives on the upper east side coming from a private school would not be grouped with, for example, a kid who grew up in Bed-Stuy and went to the local public school. However, there are a lot more UES kids at BS than Bed-Stuy kids, which is probably why the stereotype exists.