Corbett

I found some enrollment statistics by state for colleges and universities. For top-rated northeastern LACs, the five biggest northeastern states (NY, PA, MA, NJ, CT) typically account for 40-50% of the enrolled class. At Williams, the number was at the upper end of this range, which suggests that Williams may actually be less concerned about geographic diversity than some peer schools.

I don't think Williams, or any other northeastern LAC, has strict "quotas" for admitting students from specific states. But if a school is swamped with applicants from a few states, and rarely sees applicants from others, then realistically the odds of acceptance may vary. In general, any student in any state will probably get an increasing geographic advantage at schools farther from home, and will probably face stiffer competition at schools closer to home.

For top-rated LACs outside the northeast (e.g. Pomona, Carleton, Davidson), the five big northeastern states typically accounted for just 10-20% of the enrolled class. Carleton, for example, would likely prefer a well-qualified Pennsylvanian (2% of enrollment) over an equally qualified Minnesotan (27% of enrollment).