Starting July 1, USC will accept the Common Application. And with that move, Georgetown becomes the last holdout among traditional national universities in embracing a universal college application.

Admission deans have been tracking the gradual migration of top universities to the Common App, a single form that greatly eases the chore of applying to multiple colleges.

The Common App saves students time. Colleges that switch to the generic application can expect a 10- to 20-percent bump in applications. Prestigious colleges that once looked down on the form have come to embrace it as part of a competitive admissions strategy.

Over the past few years, the number of first-tier national universities refusing the Common App dwindled to a handful. Princeton and Cornell adopted it in 2004, Northwestern and Penn in 2006, Brown and the universities of Chicago and Virginia in 2008, according to a piece I wrote on Georgetown last year.

I was able to identify just three schools in that group still hewing to signature applications: USC, Georgetown and MIT.

I spoke with Timothy Brunhold, dean of admission at USC, about its application last fall, and with USC President Max Nikias on the topic earlier this year.

USC had one of the earliest and best online applications, Brunhold told me, and held onto it long after most of its peers had switched to the Common App.

But over the past few years, he said, “We got a lot of feedback from the high school counseling community, from the student community itself, telling us that [adopting the Common Application] might be the right thing to do.”

Nikias and Brunhold gave the same reasons for adopting the Common App as their counterparts at U of C and U-Va.: it’s another admissions tool that makes the college application process a bit easier for students, particularly those from more disadvantaged backgrounds. The Common App has become at least anecdotally associated with greater diversity in an applicant pool, a quality few university presidents can resist.

USC is one of 49 new members of the Common Application community this year, along with Christopher Newport University in Virginia, Howard in D.C., Towson University and St. Mary’s College of Maryland.

If the Los Angeles university witnesses the customary bump in its applications next year, the school could potentially top 40,000 applications, one of the largest totals in the nation. USC collected 37,164 applications for fall 2011, a number possibly surpassed only by Northeastern University and NYU.