I was thinking about connections between Jack Kerouac and Halloween (beyond the obvious "jack-o-lantern") -- since today is October 31 -- and so I looked for something he has said on the subject. I didn't see anything in the two editions of his letters, and I thumbed through several novels to no avail. I have On The Road as a digital document -- allowing for easy searching -- and I did find that Jack mentions Halloween three times as follows.
1. In Part One Chapter 9, Sal (Kerouac) is describing how Denver D. Doll (real-life Justin W. Brierly) has a habit of giving greetings that don't match the time of day or season:
Everybody knew him. "Happy New Year," he called, and sometimes "Merry Christmas." He said this all the time. At Christmas he said Happy Halloween. (Penguin Books, 1976, p. 54)
2. In Part One Chapter 13, the well-known section about Terry "the Mexican girl," Sal is describing the "wild streets of Fresno Mextown":
Strange Chinese hung out of windows, digging the Sunday night streets; groups of Mex chicks swaggered around in slacks; mambo blasted from jukeboxes; the lights were festooned around like Halloween. (Ibid., p. 93)
3. In Part One Chapter 14, Sal, after leaving Terry, is "going home in October. Everybody goes home in October" (Ibid., p. 103) and says:
The bus roared through Indiana cornfields that night; the moon illuminated the ghostly gathered husks; it was almost Halloween. (Ibid., p. 103)
So there you have it: all the references to Halloween from On The Road in one spot. You're welcome.
Happy Kerouac Halloween!