Despite using the Ulster name in its title, almost all of its clubs were based in County Donegal and the City of Derry.

Michael Sweeney, a pioneer of junior and intermediate association football in County Donegal.

In addition to founding the USL, Sweeney had earlier been instrumental in both establishing the Donegal League and forming Fanad United.

Cockhill Celtic, Culdaff and Swilly Rovers have all represented the USL in the League of Ireland Cup.

[4][7] Fanad United have also won the FAI Intermediate Cup twice while Letterkenny Rovers were finalists in 2015–16.