In addition to leaving an indelible mark on American folk and country music, Watson was beloved by area bluegrass fans. Over the years, he played countless concerts at Wolf Trap National Park for the Performing Arts; one Post review described Watson’s audience at a 1977 Wolf Trap gig as “a massive crowd — thousands of good country people and one Iranian empress.”

Oh, the #11 slot for nonfiction is occupied by Sarah Thomas’s strong selling “Jesus Calling” (poor Andy Cohen has slipped to #12), while over in fiction, that near-breakthrough spot is held by Stephen King’s “The Wind Through the Keyhole,” the Dark Tower novel knocked from the top 10 by fresh offerings from John Sandford and Steve Berry.

You don’t have to know Tom and Gary to come to this shindig, though, because no one else will really know them either. They’re two sunglass-wearing dudes who claim to be from the future, if by “the future” they mean Canada (and they have an ironic fashion sense firmly rooted in the 1980s, to boot). They are the ultimate party animals — currently on an eight-city American party tour which will stop in D.C. Saturday night to gather people up for a boombox blasting bacchanale in the streets.