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What’s more, the fewer employees in a workplace, the more likely they were to win elections by wider margins, underscoring that workers at smaller units are more consistent and cohesive in their support of unions. In the typical small-unit election, unions win 80 percent of the “yes” vote. For larger units, this number drops to under 60 percent.

Why, then, does organized labor focus its limited resources on organizing large workplaces, when evidence shows that it’d be more successful in smaller workplaces? A big reason is that unions continue to rely on retail organizing. Professional organizers are sent into one workplace at a time, and they try to convince a majority of workers to join a union. If a workplace is too small, or if it’s geographically isolated, or if it’s in a state with strict anti-union laws, it’s not worth most unions’ time to organize there, and so they don’t.

But what if there were a way for unions to greatly reduce the costs of organizing small workplaces, and bring that approach to scale at small and medium-sized workplaces across the country? There is—through online organizing and large-scale digital marketing to workers.

Organized labor can follow the lead of successful commercial and political campaigns, which have mastered the use of algorithms and data-mining tools to identify, engage, and influence customers and voters. Unions could use “big data” to target low-wage workers in specific locations who share traits commonly associated with union support. It’s a path toward reversing the trend of declining unionization, and recruiting millions of new members.

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Imagine a fast-food worker in Alabama who sees an ad on Facebook promoting higher wages at work by joining a union. The ad could then direct workers to a free or low-cost online organizing platform, empowering them to initiate organizing drives at their workplace by providing them with resources such as step-by-step guides to gather signatures and file petitions for union recognition.

Such a model would improve the economics of winning new members, given the relative cost-effectiveness of micro-targeting and digital marketing. Lowered acquisition costs would in turn allow unions to diversify the locations and types of workplaces at which they recruit, opening up regions of the country, like the South and the Great Plains, in which unions have historically struggled to make inroads.