Final answer:
Wearing Halloween costumes is an American tradition that started with the Irish immigrants who came in the 1800s. Halloween has roots in the ancient Celtic festival of Samhain.
Step-by-step explanation:
Wearing Halloween costumes is an American tradition that started with the Irish immigrants who came in the 1800s. Halloween itself has roots in the ancient Celtic festival of Samhain, where people believed that on the night of October 31st, the boundary between the living and the dead was blurred. To ward off evil spirits, people would dress up in costumes and disguise themselves.
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