Ordinary people joined the Nazi party. Then their Jewish neighbors disappeared.

Researchers digitized nearly all Nazi Party membership records, linking them to population and industrial census data. It turns out the party grew by drawing in ordinary people, and local membership increases were linked to the deportation of Jewish residents.

For decades, people have debated whether the Nazi party was an elite movement or a mass one. This paper shows it was both, but that its growth into a mass movement was critical. It reveals how local social networks and the presence of early members helped draw in more people, creating a direct link between community-level party growth and the deportation of Jewish residents.