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MINNEAPOLIS (CBSMiami) – Americans are expected to spend $3.5 billion on Halloween costumes this year.

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Superheroes, princesses, Batman and animals are expected to be the kid top-sellers.

Dressing up has been a tradition for generations, but how did it all get started?

“Let me dispel one of the most common misconceptions, it wasn’t to scare off evil spirits,” said Lisa Morton, author of “Trick or Treat: A History of Halloween.”

Halloween dates back 2,000 years ago, when the Celts celebrated Samhain, or the “summer’s end” in Old Irish.

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During this day of the dead celebration, some people visited homes dressed up like fairies, ghosts, witches, skeletons and evil creatures, performing various antics in exchange for food and drink.

Over the next several hundred years, costumes were common for many holidays. Children would “guise” throughout the year by asking for food in exchange for songs, dances or prayers.

Fast forward to the 1800s, when Halloween become known for pranks. The pranking started getting dangerous during that time, and towns and cities starting thinking about cancelling Halloween.

There was a gradual push from families, communities and civic organizations to change the nature of the holidays from trick to treat.

“Basically, they bought the kids off with treats and costumes,” Morton said.

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Costumes were mass-produced by the 1930s, bringing us to where we are today … sexy nurse and Elvis costumes.