Porter and Dolly. Conway and Loretta. Johnny and June. Country artists have been working on perfecting the duet since time immemorial, and 2015 brought its own share of tag-teamed performances, from Brad Paisley's onstage jam with the Rolling Stones — on a country-tinged number with references to shooting heroin, no less — to Little Big Town's gospel choir harmonies for pop newcomer Tori Kelly.
Then there was Chris Stapleton and Justin Timberlake's collaboration at the CMA Awards, an unlikely duet that single-handedly vaulted Stapleton from underground cult status to the top of the mainstream charts. Over an explosive eight minutes, the singers swapped harmonies and guitar riffs on a pair of songs that helped set a new high mark for collaborative excellence. Understandably, they've topped the following list of 2015's 10 best country collaborations, which also makes room for roots-rock veteran Don Henley, big-voiced Dixie Chick Natalie Maines and Americana kingpins Jason Isbell and Sturgill Simpson.