This article interrogates digital "story banking," a storytelling practice that has become increasingly popular among U.S. grassroots advocacy organizations. Through the examination of LinkedIn data and in-depth interviews with story banking professionals, this technique emerges as the centerpiece of the growing institutionalization, professionalization, and datafication of storytelling in progressive advocacy. Following the 2016 election, political crisis and an increasing awareness of changing information consumption patterns promoted story banking diffusion. Story banking ushers in the era of stories as data and political story on demand. Yet, political constraints currently limit story banking to a reactive approach based on news monitoring, algorithmic shortlisting of stories, and audience testing. Furthermore, an unresolved tension has emerged between the growing centralization of storytelling functions and the participatory potential of crowd-sourced story banks. The implications of these trends for progressive advocacy organizations and the groups they aim to represent are considered.