Notre Dame has been a member of the Big East in all sports except football and hockey since 1995.
A central sticking point had been the ACC's unwillingness to budge on all-or-nothing membership: Either you bring your football program or you can't join. That changed, for any number of reasons, to bring Notre Dame aboard.
"We have always been an all-in, if you will, membership," Swofford said. "In more recent years, we've discussed this with a changing landscape out there, a changing world. ... What was best 20 years ago isn't necessarily best in today's world.
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"Now's the time. This is a partnership that is a win-win, and good for both parties. The time had come to cross this threshold."
The Irish also will endeavor to protect its football rivalry games —specifically, Navy, Southern California and Stanford. As for long-running series against Big Ten foes, the Irish might rotate those opponents on a yearly basis.
The series between Notre Dame and Navy, which has been played uninterrupted since 1927, will not likely be affected. According to Midshipmen athletic director Chet Gladchuk, the current contract runs through 2025.
"We've got a wonderful friendship and relationship that goes back historically with Notre Dame. We just came back from Ireland, where we had a wonderful experience," Gladchuk said Wednesday night. "I was reading some of the press releases today and Notre Dame made a point to mention that the Navy series is something they appreciate and will continue. ... I really believe one of their priorities for more than 80 years has been Navy-Notre Dame, and I believe that will continue well into the future."
Baltimore Sun reporter Don Markus and Tribune Newspapers' Brian Hamilton contributed to this article.