The 2015 USL season was the fifth season of the United Soccer League (USL) and the first under its new name. This season represented a substantial expansion from 14 teams in 2014 to 24 teams in 2015, and the division of the league into two conferences. It is also the 29th season of third-division soccer in the United States.
The 2015 Oklahoma City Energy FC season was the club's second season in existence, and their second season playing in the United Soccer League, the third tier of the American soccer pyramid.
The 2015 Arizona United SC season was the club's second season. They played in the Western Conference of the United Soccer League.
The 2015 Sacramento Republic FC season was the club's second season of existence. The club played in the newly rebranded United Soccer League (USL), formerly known as USL Pro, the third tier of the American soccer pyramid. After offseason expansion of the USL from 14 to 24 teams and division into an Eastern and Western Conference, Sacramento Republic FC competed in the new Western Conference. The Republic entered the season as defending champions, having defeated the Harrisburg City Islanders 2–0 in the USL final on September 27, 2014. The season began on March 21 and concluded on September 20.
The 2015 LA Galaxy II season was the club's second season of existence. This season LA Galaxy II participated in the USL and the U.S. Open Cup.
The 2015 Seattle Sounders FC 2 season was the club's first year of existence, and their first season in the United Soccer League, the third tier of the United States soccer pyramid. Including previous Seattle Sounders franchises, it was the 35th season of a soccer team playing in the Seattle metro area.
The 2015 Real Monarchs SLC season was the club's first season of existence. Real Monarchs SLC competed in the United Soccer League, the third tier of the American soccer pyramid. The season began on March 22 and concluded on September 12.
The 2015 Austin Aztex season was the club's fourth season of existence. The club is now playing in the United Soccer League, the third tier of the American soccer pyramid. They were previously in the USL PDL the last 3 seasons, where they won the 2013 Championship, and the appeared in the Conference Finals in 2012 and 2014. The Austin Aztex will be competing in the Western conference and will be playing their first season in the newly dubbed USL. The season will begin March 21 and conclude on September 20.
The 2015 Colorado Springs Switchbacks FC season was the club's first season of existence, and their first season in the United Soccer League, the third division of the American soccer pyramid. The Switchbacks played in the Western Conference of USL.
The 2015 Portland Timbers 2 season was the inaugural season for the Portland Timbers 2 in the United Soccer League (USL), the third-division professional soccer league in the United States and Canada. The Timbers 2 are the reserve team of the MLS side, Portland Timbers.
The Western Conference is one of two conferences in USL Championship soccer.
The 2016 Oklahoma City Energy FC season was the club's third season in existence, and their third season playing in the United Soccer League (USL), the third tier of the American soccer pyramid.
The 2016 Real Monarchs SLC season was the club's second season of existence, and second playing in the United Soccer League, the third tier of the American soccer pyramid. The season began on March 26 at home against Saint Louis FC, and ended on September 24.
The 2017 OKC Energy FC season was the club's fourth season in existence, and their fourth season playing in the USL, the 2nd tier of the American soccer pyramid.
The 2017 Seattle Sounders FC 2 season was the club's third year of existence, and their third season in the United Soccer League, the second tier of the United States Soccer Pyramid. Including previous Seattle Sounders franchises, it was the 37th season of a soccer team playing in the Seattle metro area.
The 2017 Colorado Springs Switchbacks FC season was the club's third year of existence, and their third season in the Western Conference of the United Soccer League, the second tier of the United States Soccer Pyramid. On February 14, 2017 the Colorado Springs Switchbacks FC officially announced Weidner Apartment Homes had acquired the naming rights to the Switchbacks Stadium which has been rebranded as "Weidner Field". The team's mascot is Ziggy, who is a mountain goat.
The 2017 Real Monarchs season was the club's third season of existence, and their third season in the United Soccer League.
The 2017 Tulsa Roughnecks FC season was the club's third season of existence, and their third in the United Soccer League. It is the club's first season playing in the second division of American soccer following U.S. Soccer's sanctioning of USL as a Division II professional league. Including the previous iterations of franchises named "Tulsa Roughnecks", this is the 17th season of a soccer club named the "Roughnecks" playing in the Tulsa metropolitan area.
The 2017 Swope Park Rangers season was the club's 2nd year of play, along with their second season in the Western Conference of the United Soccer League, the second tier of the United States Soccer Pyramid. For the 2nd straight year the Swope Park Rangers finished fourth in the Western Conference and were runners-up in the USL Championship; they lost 1-0 to Louisville City FC in the final.
The 2019 Real Monarchs season was the fifth season for Real Monarchs in the United Soccer League Championship, the second-tier professional soccer league in the United States and Canada.
