There are 3 different USTA Summer Leagues:

Summer Singles: The North Carolina Singles League is a team competition for Men and Women with NTRP levels of 2.5 to 4.5. Each match is three singles courts.

Tri Level: Play doubles with your friends while on a team consisting of 3 or more NTRP levels! Example, one 3.0 doubles, one 3.5 doubles and one 4.0 doubles = Tri-Level team. 

Mixed Doubles:  USTA League Mixed Doubles is a team competition for men and women with NTRP levels of 2.5 to 5.5. Winning local teams advance to the NC State Championship. Winners of the NC State Championship advance to the Sectional Championships. Teams are formed using combined NTRP levels of 5.0, 6.0, 7.0,8.0, 9.0 and 10.0.