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
When we look back at 2020 in the business world, we'll remember it as the year online shopping stopped being the future of retail and became the present.
Context & Ripple Effects
This closes the loop on a year of escalating forecasts: eMarketer's mid-year projection had US consumers spending $710B online in 2020, up 18% YoY ($710B online in 2020), and the full-year estimate lands even higher — 30%+ growth against a recent baseline of 12%-16% annually. Amazon is the outsized beneficiary, with its US retail business estimated to have grown 39% YoY, extending the dominance eMarketer already measured in 2018 when it projected nearly half of all US online retail spend flowing through the company.
The significance cuts both ways: later data shows e-commerce's share of total US retail has since fallen back toward pre-pandemic levels as in-store sales recovered (e-commerce's share of US retail pulling back), making 2020 look less like a permanent reset and more like a compressed, one-time acceleration.
First-order effects
- Amazon ends 2020 with its US retail business roughly 39% larger than a year earlier — growth concentrated in the single year that online shopping became 'the present' rather than the future of retail.
- US e-commerce overall grew at more than double its recent annual pace, meaning retailers' digital channels absorbed demand far faster than their pre-2020 capacity plans assumed.
Second-order effects
- Amazon's retail scale directly fed its advertising business: eMarketer later put Amazon's US digital ad share at 10.3% in 2020, up from 7.8%, with revenue estimated at $15.73B, up 52.5% YoY (Amazon's digital ad share climbing to 10.3%) — brands following shoppers onto the platform.
- Rivals and suppliers spent 2020-2021 building against a peak-demand baseline, which helps explain why e-commerce share retreating toward pre-pandemic levels by early 2022 left the industry with excess digital infrastructure relative to actual demand.
Third-order effects
- If the pattern holds, 2020 was a step-change in absolute online spend that persisted even as the share of retail reverted — leaving Amazon structurally larger and structurally more entrenched in both retail and the retail-media advertising market it monetizes on top.
- The gap between the 30%+ spike and the subsequent share reversal sets up the industry's central planning problem: capacity and investment decisions calibrated to pandemic peaks versus a slower underlying growth trend.
The trend: US retail is consolidating around Amazon's platform economy — where retail scale compounds into advertising power — with 2020 marking the inflection point that pulled the future forward by several years.