Why was the day after Thanksgiving originally called 'Black Friday' in the retail world?

Test your knowledge about one of retail's most significant shopping events! Black Friday has transformed from a local phenomenon to a global retail holiday that shapes marketing strategies, supply chains, and consumer behavior worldwide. Behind this shopping extravaganza lies an interesting origin story that many retail professionals should know, but often don't. Can you identify how this retail phenomenon got its name?

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Because retailers would finally turn a profit for the year (go from 'in the red' to 'in the black')
Because of the dark crowds that would form outside stores before opening
Because it was originally a day when stock markets crashed in 1869
Because Philadelphia police used the term to describe the chaotic traffic and shopping crowds