Duke most definitely pushed the party scene off campus, and the result was predictable and inevitable. That happened a long time ago (not long after the drinking age was raised to 21). What the recent press reports suggest is that Durham finally got sick of dealing with what it considered to be Duke's problem. At the same time, Duke built these dormitories that were at less than capacity. In other words, Duke cowardly foisted the party problems on Durham instead of dealing with it itself, and when those problems got out of control off campus, turned a blind eye as Durham cracked down and made life miserable for Duke students. Duke and Durham PD played this little game because it was in both their interests for the last few years (as evidence by the threatening letter to students living off-campus, Gottlieb's arrest records, etc.). What changed was Nifong.
I find Duke unusual in that it requires students to live on campus through their junior year. Were seniors living on campus when you were there? My student lives on campus as a senior because it is convenient. And I was surprised to find that many in the circle of friends, also seniors, were staying on campus also. I do recall the room next to student's was empty in her soph year. The resident had to pay for the room because s/he wasn't a senior; but actually lived in an apt. off-campus. I know that Duke is unusual in that it requires residency for 3 years; but is it unusual in trying to control drinking on campus?