"MLK" originated from a melody and set of lyrics composed by lead vocalist Bono while listening to the pitched hum of his vacuum cleaner.
According to guitarist the Edge, the band "failed miserably" to find a musical arrangement that suited the melody and that the results "always sounded far too traditional".
It went into another hiatus after PopMart, missing the entire Elevation Tour, but was notably performed as the intro to "Where the Streets Have No Name" at U2's appearance during the Super Bowl XXXVI halftime show in 2002.
After the death of Rosa Parks, it made five Vertigo Tour appearances; in all five instances, it was sung after "One" to conclude the main set.
[2] "MLK" was director Richard Kelly's original choice for the soundtrack to the final sequence of the 2001 film Donnie Darko.