‘Winding Stream' tells story of country's Carter and Cash families

American royalty gets a well-deserved encomium in Beth Harrington’s fond documentary, “The Winding Stream: The Carters, the Cashes and the Course of Country Music.”

Thoughtfully assembled to showcase the music and the temperaments behind it, this jam-packed oral history of the Carter and Cash families weaves the voices of prominent musicians (Sheryl Crow, George Jones) with those of family members past and present. Leading us from Poor Valley, Virginia - where the seventh generation of Carters still attends the church that its patriarch, A.P., built in 1906 - through decades of personal and professional landmarks, Harrington sweeps divorce, disappointment and the Great Depression into a single, upbeat package.

With music like this - Rosanne Cash calls it “primal” - that’s not hard to do. Rooted in the folk songs of Appalachia, the playlist of the original Carter family grew and was spread in those early years by the powerful signal of a Mexican radio station. Performed by A.P., a traveling salesman and inveterate impresario, his wife, Sara, and her cousin Maybelle, the tunes would prove indestructible. Not even Pearl Harbor - which supplanted a Carter feature in Life magazine and inspired a family joke that they had been “bombed out of their career” - could stop them.

Rhythmically blending vintage recordings and live performances, “The Winding Stream” exudes a quirky warmth that counters its PBS-pledge-drive aura. Mike Olson’s photo-animations have a Terry Gilliam-like oddness, and, despite a welcome interview with Johnny Cash (conducted just weeks before his death in 2003), it’s the Carter women who shine. Maybelle’s virtuosic ability to play rhythm and lead guitar simultaneously; June’s flair for comedy; Janette’s Saturday-night hoedowns at the Carter Family Fold, where neither drunkenness nor dirty dancing was allowed.

Hints at Johnny Cash’s demons aside, Harrington, like her subjects, doesn’t dwell on the darkness. Obeying one of the Carters’ most famous songs, she prefers to keep on the sunny side.