Well. They are ranked #1 by the National Law Journal in their "go-to" schools list. Read the lead article in NLJ here. See the NLJ rankings here. Remember, these rankings reflect the law schools with the highest percentage of graduates hired by the NLJ's top 250 firms.
Why the #1 ranking? Read this post by Dan Filler blogging for the Faculty Lounge. Apparently, at least one Northwestern professor, Steve Lubet, thinks that Northwestern holds the number one position because of its strong clinical and skills program. At least that's what he says in this article from the Daily Northwestern.
Regardless of whether you agree with the ranking, it is interesting to see law schools paying attention to the findings of the MacCrate and the Carnegie reports.