For the last four years, members of indie-rock band the National have been working on "Day of the Dead," a massive, 59-song tribute to the Grateful Dead. Making up the six hours of music is a diverse roster of acts from the indie-rock and Americana scenes, including Wilco, Lucinda Williams, Courtney Barnett, My Morning Jacket’s Jim James and many more.

For a good portion of the tracks, the National served as a house band of sorts - inviting musicians to a converted church in upstate New York to record vocals with...