While in New York for the All for the Hall concert benefitting the Country Music Hall of Fame and Museum, Radio.com caught up with Harris, and she filled us in on just why the duo made us wait so long.

"We were busy. We're both road dogs," she said. "We're always out there touring or making a record, working a record."

Harris and Crowell have known each other since the 1970s, when Crowell was a member of Emmylou's famous Hot Band. However, as Emmylou explained it, "There didn't seem to be any urgency" for an album featuring just these two music legends. They each, after all, had very successful careers on their own, including more than a few best-selling albums and Number One hits.