In a world where the political gender gap is growing as women move left, a clever grassroots campaign is reminding women of a fundamental truth: Their vote is private. This guerrilla movement uses a simple yet powerful tool—Post-It notes—to reach women whose partners may disagree with their political choices.

The premise is simple: small, brightly colored notes discreetly placed in public spaces, like bathroom stalls, libraries, cafes, dorm buildings, workplace lounges, doctors’ offices and community boards. Each note carries the message that every woman has the right to cast her vote freely and privately.