Mikayla Nelson, left, and her sister Mykenzie Nelson sport some homemade masks and their Halloween T-shirts at the Special Kids Day Pumpkin Dance at the Knights of Columbus Hall in Chippewa Falls.

The co-host of NPR's "Throughline" podcast, Rund Abdelfatah, once cited Halloween as "an American capitalist success story." What began as a Celtic tradition called Samhain now operates as a ...