Ethan Chernofsky | Source | Vice President of Marketing at Placer.ai

Amazon.com's dominance in online retail is clear to see: The so-called Everything Store captures 49 percent of retail e-commerce sales in the U.S., thanks in large part to its 95 million-strong army of Prime customers, who in July contributed to an estimated $4 billion spent globally in just 36 hours during a promotional binge that Jeff Bezos created out of thin air. For comparison, that's more than Church & Dwight, maker of Arm & Hammer baking soda and Trojan condoms, generates in a year. So Amazon's the biggest shopping site in the U.S. But is it the best? And how does one measure that, anyway? A common way is to look at how much of a retailer's total revenue comes from its online division.

Store closures for the first half of 2019 have already exceeded all of 2018, but many of them are positive signs of a retail restructuring.