I only applied to Mercersburg because of the swimming program.
The reason why other people chose to go to Mercersburg is because of financial aid. Apparently, they give out a lot of financial aid even though the economy is pretty bad.
Mercersburg was the only boarding school I applied to, I came here because in my parents culture (Nigerian) sending kids to boarding school is extremely common. (My mom left when she was in 6th grade). I personally, have always been independent, and didn’t want my parents looming over me during my high school years. And I liked Mercersburg because of its diversity—I literally have friends from all over the world— and because it was still close enough for me to run home whenever I felt like it. Also as Val said, the financial aid deal was pretty sweet.