I wholeheartedly agree with bb.
The thing about Tuck is that it's so easy for someone who feels ambivalent about the school to find a reason to go somewhere else. The remote location is a highly effective filter that ensures only the most passionate people
accept the invitation to matriculate (in fact, the location keeps a lot of people from applying in the first place, which is great). Though some may apply without visiting, most won't accept until after they've visited and fallen in love.
There are a few things that ensure Tuckies are super close:
Everyone's out there, together and alone. What I mean is that Tuckies have each other and ONLY each other, 2.5 hours from Boston. No one moves to Hanover already knowing a bunch of friends in the area. No one grew up in Hanover. No one is skipping the MBA party in favor of some other local party. Hanover has a population of 11,000. Dartmouth has 6,000 students, and the other 5,000 residents feed, clothe, and otherwise support the students. Your only social/intellectual/emotional stimulation is likely to come from other Tuckies.
Any top MBA is harsh, but winter in Hanover kicks things up a notch. When you survive something harsh with others, there's a natural sense of camaraderie.
There aren't a whole lot of Tuckies. Small class sizes mean that you know everyone. It means that you get personal attention and support from peers, faculty, and staff. Therefore, it's natural for Tuckies to feel a lot of gratitude and pay it forward. It's a virtuous cycle.
I can't comment on Kellogg, as I haven't visited the campus (campus visits for the fall semester had already ended by the time I applied/returned to the US). But I'm sure they don't have the closeness I saw when I went to Tuck.
About a third of students were in Tuck-branded clothes.
Anytime a student was headed towards/returning from the interview rooms, other students addressed him by name and wished him luck/asked how it went.
The professor of the class I observed had me introduce myself before he got started. I spoke for about 30 seconds and the whole class applauded me for about the same length of time. They are just so damn amicable.
Tuck spirit is a veritable force to be reckoned with. I feel it, and I only spent 6 hours there!