The Big East has acquired all the pieces needed to build a new coast-to-coast conference. Putting them all together, though, is going to take awhile.

The conference wanted to rebuild itself into a 12-team football league that can hold a championship game, and Memphis officially became that 12th member on Wednesday when it accepted an invite it has long coveted.

But the new Big East isn’t scheduled to be fully functional until the 2015 football season. As for the next three years, what the Big East will look like is anybody’s guess.

Memphis is the seventh school, and fourth from Conference USA, to sign up since December for future membership in the Big East. The Tigers will compete in the Big East in all sports.

“It certainly is an historic day for us,” University of Memphis president Shirley Raines said during a teleconference with Big East commissioner John Marinatto and Memphis athletic director R.C. Johnson.

Memphis has been trying to upgrade its conference affiliation for years, and the Big East was always the most likely landing spot. The Tigers were snubbed during the Big East’s last massive expansion in 2005 and lost a longtime rivalry with Louisville in the process.

Now with the Big East in need of replacements for West Virginia, Pittsburgh and Syracuse, there was finally room for Memphis.

Marinatto has traveled across the country in recent months to recruit new members. In December, the Big East announced Boise State and San Diego State from the Mountain West Conference would join in 2013 for football only, and Houston, SMU and Central Florida, from C-USA, would become members in all sports.

Last month, Navy football jumped on board, though that won’t happen until 2015.

The Big East pitched Air Force and BYU on joining, but couldn’t work out a deal with either. Temple also was being considered, but the Philadelphia school and former Big East member was passed over for Memphis because the conference wanted to bolster its new west wing.