It's been rumored for months, and on Wednesday afternoon MLS and USL Pro made it official: The two leagues have reached an agreement to integrate MLS Reserve League teams into the USL Pro schedule, a multi-year deal that will feature "interleague" play between MLSRL teams and the 13 USL Pro sides.

In the year ahead, that deal also includes affiliations for select teams, facilitating loans from MLS to USL Pro clubs (the third tier of the US soccer pyramid) for players who otherwise wouldn't get much playing time in the top flight. The goal is to immediately improve professional player development in the United States and Canada, providing more and better competition for young pros with big-league dreams.

The coming months will also see joint "technical and commercial initiatives" between the two leagues as the details are ironed out.

“This partnership represents the first step in a long-term alliance between MLS and USL Pro to connect domestic professional soccer through a system that benefits player development, competition and the overall business of our sport,” said MLS executive vice president of player relations and competition Todd Durbin in a press release. “Over the past several years, USL Pro has made great strides in restructuring in a manner that serves to complement the objectives of MLS. This is a win-win for all involved and it demonstrates our strong commitment to growing North American professional soccer at all levels.”

Currently there are 13 USL Pro clubs, including six in the Southeastern United States, an area in which MLS Commissioner Don Garber has talked openly about expanding the league's footprint. Two USL teams — VSI Tampa Bay FC and Phoenix FC — are set to kick off this year. A 14th team based in Sacramento will enter the league in 2014.

As it stands, each of the USL Pro teams will play a pair interleague games against MLS Reserve teams. USL Pro teams have been paired with a single MLS team to play a home-and-home series, save for Antigua, who will play both games at the site of the MLS team. The interleague games will count in both the official USL Pro and MLS Reserve League standings.

Club affiliations between MLS and USL Pro sides will be tailored to the needs of each specific team, and will include at least four MLS players going out on a long-term loan to their USL affiliate. Last year Portland's Bright Dike parlayed a good summertime run of form with the LA Blues into a starting job with the Timbers down the stretch, and several other players spent time honing their skills with USL Pro clubs.

The MLS Reserve League provides meaningful competition for players who are not regulars in the first team’s matches such as young players, players returning from injury, and youth development products. Each of the 19 MLS clubs will field either a Reserve Team or establish an affiliation with a USL PRO club.

MLS teams with formal USL Pro affiliates will not play in the 2013 MLS Reserve League. No clubs are required to enter into an affiliation, and specific affiliations will be announced in the coming days.

“USL Pro has for the past several years been the most sophisticated and competitive professional soccer league under MLS,” USL CEO Alec Papadakis said. “This new partnership with MLS will elevate and strengthen the level of competition for domestic professional soccer while simultaneously creating a more sustainable financial model for team owners. As a result, we expect this partnership will forge a seamless system for the development of players and coaches, and promote the expansion of professional soccer into new North American markets.”

Details of the fixtures will be announced in conjunction with the forthcoming release of the official 2013 USL Pro schedule.