richmond.com has a history of Halloween on Hanover Avenue:
It’s difficult to determine the exact year that the 2100 block’s Halloween celebration started. According to Mrs. Forsyth, there had been notable seasonal activities on the block for many years prior to the late-1970s, when my family first moved to Richmond.
A write-up in the November 4, 1987, issue of the Richmond News Leader offers some temporal context for the first coherently themed block party. “The block’s celebration has grown like a mutating plant over the past decade,” and he offered my mother’s words to describe the affair’s origin: “’We moved here about 10 years ago from Vermont,’ recalled Miss Imajo, credited by neighbors as creating the idea of the Halloween block. ‘I had four little kids, and I didn’t want them out trick-or-treating in the big city.’”