How Bernie Sanders accidentally built a groundbreaking organizing movement

For all its revolutionary sensibility, the 2016 campaign was organized around a traditional strategic approach: Raise money to put ads on television and fund a field operation in key early states.

But outside of the watch of the campaign’s top brass, a collection of activists working in the bowels of the campaign tested out a variety of experimental approaches to organizing, eventually producing a breakthrough that has been copied by organizers in Spain and the U.K.; helped elect Alexandria Ocasio-Cortez to Congress; and is now guiding Sanders’s 2020 campaign. Sanders built this movement, however, largely by accident.