Plastic Bag Ban Success Hard to Gauge—For Billions of Reasons

Americans use more than 380 billion single-use plastic bags a year. Or do they?

That figure was the one advocates in New York cited when they pushed successfully for a statewide bag ban that takes effect next month. And it came up again in news reports when Oregon’s ban took effect Jan. 1.

Google search results show the statistic surfacing on millions of websites across the globe, in everything from blogs about sea turtles to municipal government websites.

And more and more states across the country are relying on that 380-billion-bags-used-annually data point in order to estimate ...