Did Lovecraft ever mention Halloween as a day of pranks? Well, he knew of its prankish traditions. In his Department of Public Criticism (January 1919) column he gives a few comments on the contents of The Brooklynite for November 1918…

Mr. A. M. Adams is more successful as an essayist, and manages to infuse some real, glowing, and practical patriotism in his colloquial discourse on “Halloween Pranks”. We are glad to see so virile a piece at this particular time…

But no, he doesn’t discuss it in any volume of letters I have access to, either historically or in terms of mentioning that neighbourhood kids had come knocking on the door offering ‘trick or treat’. Though there are headers in a couple of letters. On 31st October 1931 he dated a letter to Cole as simply… “All Hallows”, and two years later he did the same with a letter to Morton.

So far as I can tell the letters hint only twice at any sort of Halloween activity on his part. To Dwyer, on being sent a drawing of Pickman’s Model, he comments (3rd March 1927) that…

At Roodmas and All-Hallows’ shall I view it, and the Objects squatting on nearby coffins or peering monstrously over my shoulder shall shudder as they gaze upon its forbidden revelations.

Remarking to Donald Wandrei (3rd November 1927) on his recent reading of The Aeneid in the 1906 James Rhoades translation, he also comments on his “spectral thoughts” at Halloween…

This Virgilian diversion, together with the spectral thoughts incident to All Hallows’ Eve with its Witch-Sabbaths on the hills, produced in me last Monday night a Roman dream of such supernal clearness & vividness, & such titanic adumbrations of hidden horror, that I verily believe I shall some day employ it in fiction.

And that’s about it so far as I can tell, apart from the use in fiction. No comments in letters on the local tradition of “Halloween pranks”, if such things were even permitted in Providence. Though admittedly I don’t yet have the two volumes of his letters to his aunts, so may be missing some mentions in letters. But I’m sure S.T. Joshi’s I Am Providence would have noted any in-person trick-or-treating in company with his aunts (“I’m H.P. Lovecraft, I don’t need to wear a mask…”). Given the evidence above he might have marked the date merely with some “spectral thoughts” and perusal of a few especially shuddersome sketches. Possibly it also often marked more or less a terminal date for his summer walks, and the onset of his usual winter hermitage.

Though he did leave us this March 1926 National Amateur poem, later reprinted in the September 1952 issue of Weird Tales…

If written for Halloween 1925, as seems likely, this would make it a poem from the Red Hook period. A time in which Lovecraft trekked out (often in vain) on what he called “exploring trips” to find relatively unspoiled suburbs of New York City. There he might find a place to walk, often at night, and enjoy for a while a lingering old-time atmosphere and the occasional company of a wide-eyed cat or two. His 1925 Diary seems to confirm my supposition: 28th Oct “Paterson” [he visits Morton in Paterson]; 29th Oct “Start poem”; 30th Oct “Finish poem”.

This doesn’t mean that the ugly suburb of the poem is Paterson, but that the trip there may have sparked the idea of the poem.

A letter adds to the Diary, and suggests why he might have been in the mood to write. Just before starting the poem he had heard that afternoon that Weird Tales had accepted his story “The Horror at Red Hook”. Also, we learn that the landlady had finally put a fire in the furnace of his until-then unheated building.

For Halloween itself the Diary shows he met Kirk and Loveman, and the Kalem Klub meeting that developed broke up at 5am the following morning. Lovecraft wandered back through the darkened streets to his room in Red Hook. The evening appears to have been marked by no special festivities, though it is quite possible his new Halloween poem was read there. So we do have, perhaps, some hints that Lovecraft marked at least one Halloween by penning a new poem.

Perhaps anticipating the acceptance of “The Horror at Red Hook”, a few weeks earlier Lovecraft had been considering how to sprinkle his writing with more convincing occult mumbo-jumbo than that he had briefly used back in the summer in “Red Hook”. In a letter to Smith on 9th October 1925 he remarked…

I have frequently thought of getting some of the junk sold at an occultists book shop in 46th St. The trouble is, that it costs too damned much for me in my present state. [and he then asks Smith for] a more or less brief list of magical books — ancient & mediaeval preferred — in English or English translations.

… presumably to see if the various New York Libraries might have free copies he could make notes from. Or perhaps the list of titles might be passed to those in the book trade, such as Kirk or Loveman, who might know of a reprint.

What of the “46th St.” occult bookstore he mentions? It can’t be the famous Weiser store, as that did not open until 1926. Possibly Lovecraft had been taken to the Gotham Book Mart, and was mis-remembering 45th as 46th? Because the famous bookseller and anti-censorship champion Frances Steloff had opened this in 1920 (a 1921 Publishers Weekly has it at “128 W. 45th St”). According to her biography her shop only sold books she liked — her tastes being almost entirely in the then-emerging modernist literature and spiritual/occultist books. One can imagine which section of the shop Lovecraft headed toward. That the books were all too expensive for him, and perhaps also too ponderous, may have been part of the impetus toward inventing his own rather more lively mythos.

He did, however, later recall seedier New York sellers of such material…

“the mystic bookstalls with their hellish bearded guardians … monstrous books from nightmare lands for sale at a song if one might chance to pick the right one from mouldering, ceiling-high piles”