ON THE BORDER marked a point of transition for the Eagles, a halfway point between their original country-rock sound and the slick pop-rock they would later embrace. The arrival of guitarist Don Felder helped eventuate this shift, even as founding member/multi-instrumentalist Bernie Leadon found himself increasingly alienated by the move away from his rootsier orientation. "Midnight Flyer," the smash hit "Already Gone," and Leadon's "My Man," an elegy to Eagles influence Gram Parsons, are the remaining traces of the band's old sound.
The title track finds the band flirting with the disco-funk sound they would pursue further on their subsequent album ONE OF THESE NIGHTS. "The Best of My Love" is the kind of flawlessly constructed '70s radio staple for which the term soft-rock was invented. The band's cover version of the Tom Waits ballad "Ol' 55" was perhaps the furthest from its origins any Waits composition would get until Rod Stewart took on "Downtown Train" many years later. In all, ON THE BORDER effectively represents the eclectic but expertly blended mix of styles that pushed the Eagles to the top of the '70s rock heap.