STORY: When it comes to back-to-school sales, retailers across the U.S. share a common conundrum: how to beat Amazon.

That's why major chains including Walmart and Target are offering discounts even earlier this year, hoping to capture dollars ahead of their online rival's signature event: Amazon Prime Day, held July 16 and 17.

Target on Sunday launched a week-long sales promotion, two days earlier than last year, offering 30% off on school uniforms and backpacks.

Walmart is holding its "largest deals event ever" from Tuesday to Thursday, also two days earlier than last year.

Online retailers Shein and Bytedance's TikTok Shop are also jumping in early.

Shein is holding a seven-week back-to-school sale starting July 15, two days ahead of its sale last year and a day ahead of Prime Day.

And TikTok Shop is running a deals event from Tuesday to July 17.

Last year, Amazon had its biggest single day of sales in the company's history on the first day of Prime Day, with sales totaling $12.7 billion.

Overall, consumers last year spent a record $41.5 billion on back-to-school items for children in kindergarten through 12th grade, according to the National Retail Federation.

With college students included, that number ballooned to $135.5 billion.