black friday
Amazon is weakening Black Friday.

Andrew Kelly/Reuters

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Amazon is permanently changing Americans’ holiday shopping calendar by celebrating Black Friday-style sales in July.

The ecommerce giant is holding its third annual Prime Day on Tuesday, and it’s expected to be bigger than ever before.

Amazon started the sale several hours earlier this year, compared to the last two years, and more than a dozen other major retailers are now taking part by offering their own massive sales events to counter Amazon.

Toys R Us, for example, is having its biggest sitewide sale of the year now through Wednesday, and Macy’s is offering 60% off its entire website on Monday and Tuesday.

JCPenney meanwhile is holding a “Penney Palooza” sale,…