eMarketer: US e-commerce sales, up 12%-16% in recent years, will have grown by 30%+ in 2020 and Amazon's US retail business grew an estimated 39% YoY in 2020
Context & Ripple Effects
eMarketer spent 2020 revising upward in real time: its July forecast already had US consumers spending $710B online at an 18% annual clip with e-commerce hitting a record 14.5% of retail, and Adobe's transaction data showed the spring lockdown spike was not a blip — online grocery up 110% and electronics up 58% in April alone. Today's year-end estimate closes the loop: full-year growth of 30%+, roughly double the 12%-16% pace of recent years.
The reason this matters beyond the headline number is who captured it: Amazon's US retail business grew an estimated 39%, outpacing the market itself, which is why the same research shop later found Amazon's share of US digital ad spending jumping from 7.8% to 10.3% as sellers chased that volume.
First-order effects
- Amazon outgrew the overall US e-commerce market (an estimated 39% vs. 30%+) in its biggest single-year expansion, consolidating share precisely when rivals' stores were closed or constrained.
- eMarketer's estimate confirms the mid-pandemic forecasts were conservative — the July projection of 18% growth ended the year closer to double that.
Second-order effects
- Merchants followed the shoppers onto Amazon's platform: its US ad revenue grew an estimated 52.5% in 2020 as brands bid for placement against surging first-party retail traffic.
- A 30%+ year pulls future demand forward, and the corpus bears out the hangover — by Insider Intelligence's later count, Amazon's US e-commerce growth had slowed to just 0.2% in 2021.
Third-order effects
- If the pull-forward pattern holds, the durable legacy of 2020 is not the growth rate but the level: e-commerce's record share of US retail sticks while growth rates mean-revert toward pre-pandemic norms, leaving share battles — not market expansion — as the main contest.
- With Amazon holding roughly 39% of US e-commerce through the slowdown, competitive pressure shifts to whoever can grow despite a flat market, raising the stakes for logistics, advertising, and pricing advantages.
The trend: The pandemic did not create a permanently faster e-commerce economy — it pulled years of adoption into 2020, resetting online's share of retail higher while growth rates snapped back, leaving Amazon's outsized share as the lasting feature.