The transition was a result of the collaboration with the current tenants, the Harrisburg Senators, and to keep pace with the standards being implemented by the USL.

During the 2015 edition of the competition, they were eliminated in the third round after conceding three goals in extra time to the Rochester Rhinos.

In 2016, the City Islanders advanced through to the fourth round, where they were ultimately defeated in stoppage time by their former MLS affiliate, Philadelphia Union.

After a stoppage time equalizer was scored by Bobby Warshaw in the 91st minute, the Union drew a late free kick outside the 18 yard box.

The free kick was subsequently shot into the net by Roland Alberg in the third minute of stoppage time.