Airbnb is not your typical company trying to defend its interests in the political process. Its power doesn't come from donations or ties to politicians. Its users are intimately invested in how the company is regulated, in ways that car-buyers or cable customers or airline passengers are not. Those users are becoming very, very numerous.

And — most important — Airbnb has the ability to reach tens of thousands of them in a single city instantly.

In San Francisco, the company says 138,000 residents have used the service in 2015, either as a host (about 6,000) or a guest somewhere (132,400). That's the equivalent of 17 percent of San Francisco's  population. And Airbnb contacted all of them in the run-up to a citywide vote Tuesday on a proposition that would have tightly restricted short-term rentals.

That's an enormous number in a city with about 446,000 registered voters. And that's a larger number of warm bodies, it turns out, than actually voted on Tuesday.

The company was very intentional in how it wielded those numbers to its advantage: "We needed to take a look at how we could potentially use the enormous base of our community and change what the voter pool would look like," Airbnb's head of global public policy, Chris Lehane, said in a media briefing after the vote.

Every host and guest in San Francisco, for instance, saw a notice like this when they visited the site:

Similar notices were included on host dashboards and in e-mails confirming local bookings.

That strategy recalls how Uber, another tech startup with political challenges, a big user base and a digital Rolodex, beat back an attempt in New York City to restrict its business earlier this year. Uber built its political campaign right into its app, famously deploying a window that showed what service would look like if Mayor Bill de Blasio's legislation passed.

Uber contacted more than 2 million New Yorkers who had given the company their information while using the service (or driving for it). And officials weren't shy in pointing out that that number far surpassed the share of New Yorkers who voted for de Blasio in his mayoral primary.

The very technology that has made these companies so alluring to consumers — their digital match-making and ease of online booking — has also made them instant powerhouses at political organizing. Airbnb touted that fact on Wednesday. Its presentation to the media included the slide above, showing that it also has more manpower in San Francisco than the tech industry.

Now as Airbnb begins to think about replicating what it did in San Francisco in other markets, Lehane points out that the company has a whole lot of users in some other big U.S. cities, too. In Washington, D.C., those users — and you just need to try the service once to give the company your contact info — amount to nearly 11 percent of the local population: