The 16 schools left in the NCAA tournament are, by the tournament’s standards, the worthiest college basketball teams in the country. But a glance at these campuses reveals another thing they have in common: They are some of the country’s finest habitats for “bros.”

There is no standard definition for what makes a person a “bro,” but you generally know one when you see one. They are mostly male students from the East Coast who join fraternities, gravitate to majors in finance and can tell you exactly how many beers they “crushed”...