It makes sense that jazz, blues, and country acts often experience the longest musical careers: The three genres are all wholly American constructs, and as such, they constitute the most basic building blocks of modern popular music. Practitioners of traditional music always fit in at least somewhat, no matter the cultural atmosphere, and the malleability and adaptability of their respective styles often allows them to contribute creatively well into old age. Linda Ronstadt and Emmylou Harris aren't especially old, yet compared to the Shania Twains of the worldor, for that matter, the likes of LeAnn Rimesthey stand as sage-like standard-bearers. The secret to the long-running success of both Ronstadt and Harris has been their keen interpretive abilities. That skill is just one more key trait of jazz, blues, and country players that allows the genres to move with the times: Old songs can be made new again when given fresh voices and arrangements. On Western Wall, the songs the duo chooses to recreate are often relatively contemporaryalong with several original compositions, selections include tracks from Bruce Springsteen ("Across The Border"), Sinéad O'Connor (the gorgeous "This Is To Mother You"), and Leonard Cohen ("Sisters Of Mercy")but the cyclical principle behind recording covers remains intact. Ronstadt and Harris have worked well together before, notably on the two Trio albums with Dolly Parton, and here, their voices sound as pure as ever. Produced by the legendary Glyn Johns and featuring Neil Young and The McGarrigle sisters, the record exudes a timeless spirit that only the experience of two remarkable singers can capture. Whether covering Patty Griffin or collaborating with Luscious Jackson's Jill Cunniff, they prove that with time comes an even greater affinity for music both original and traditional. Julie Miller's career is still in its early stages, but Broken Things indicates that she, too, may enjoy an especially long and varied creative life. (Harris even appears on the record, along with Steve Earle, Victoria Williams, and Miller's husband Buddy.) Unlike Western Wall, Broken Things' songs are all originals, but such tracks as "Orphan Train," "All My Tears," and "Maggie" are so strong that Miller shouldn't be surprised if more people start covering her songs. Harris, in fact, already included a strong version of "All My Tears" on her Wrecking Ball album, showing that the circle of traditions The Carter Family sang about remains unbroken and ever-expanding.