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We just hit an e-commerce tipping point, and Amazon — specifically Amazon Prime — is a big part of the reason why. According to a new survey from UPS and comScore, 51% of purchases are now made online instead of in a physical store, up from 48% last year and 47% in 2014. Most people did a combination of online and in-store research and browsing, and a shrinking number shop without going online at all.

Shoppers today are more comfortable using mobile devices not just to browse, but to buy: The survey found that 44% of people who own a smartphone said they'd bought something using it, up three percentage points from last year. Since we don't even need to be in front of a computer, we can literally buy things from anywhere we have cell service. Another big factor seems to be the growing embrace — by retailers and customers alike — of two-day shipping.

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One disadvantage e-commerce has always had to malls and big-box stores is its lack of ability to deliver instant gratification. We don't like to wait, and increasingly, we're not. The survey found that 20% of online shoppers want two-day shipping, double the number from just two years ago. "Amazon Prime is likely driving this increase as members select two-day shipping 31% of the time, on average, compared to an average of only 8% for non-members," the survey said.

This is bad news for Amazon's brick-and-mortar competitors. “There’s going to be severe continued pressure on department stores because traffic is going to peel away from that channel towards Amazon,” analyst Randal Konik told the Wall Street Journal.