Airbnb's headquarters was occupied by activists today

The campaign over a San Francisco ballot measure that would impose tougher limits on Airbnb rentals has inspired quite the political battle in the tech capital. It’s a battle that resonates nationally as it pits public policy makers against a tech giant that has single-handedly changed urban housing markets across America — especially in housing-strapped San Francisco. .

Airbnb has sunk a reported $8 million into defeating Prop F, hired a Clinton-era political operative and shrewdly enlisted throngs of Airbnb hosts to come to its defense. The response, though certainly not as well-financed, has been equally loud: the company was forced to apologize for an overly aggressive ad campaign that attracted backlash by for example, suggesting that San Francisco’s libraries didn’t deserve the tax money. And on Monday, the day before voting, activists temporarily set up camp in Airbnb’s lobby to voice favor for Prop F.

Prop F, known casually as the “Airbnb Initiative,” would put a 75-day limit on all forms of short-term rentals, prohibiting websites from listing units that exceed the cap. If passed, it would affect vacation rental companies like HomeAway and Flipkey. But as the biggest player in the market, Airbnb certainly stands to lose the most. Voters head to the ballot box on Tuesday.

In a city where tech industry wealth has exacerbated an already broadening wealth gap, Prop F has struck a nerve. Airbnb, backers of Prop F say, have made the city’s affordable housing crisis worse by taking long-term rentals off the market to be used as ad-hoc hotels by Airbnb guests.

And in San Francisco,  as author Steven Hill points out, multiple studies have found that 40 percent of the company’s revenue comes from hosts with multiple listings, an indication that they are renting out properties they don’t actually live in, as is intended. A San Francisco Chronicle investigation found that at least 350 homes listed on Airbnb in San Francisco appear to be full-time rentals.

But San Francisco Mayor Ed Lee and others have criticized the proposition, saying that it will limit the ability of hosts to rent out their apartment to pay their bills. The Chronicle’s editorial board also endorsed a no vote, arguing that the issue is one for lawmakers to tackle directly, not a public referendum that cannot be easily tweaked when another Silicon Valley company changes the market yet again. One host, a 75-year-old former social worker, told Bloomberg that Prop F is “just too draconian, too extreme.”

But Prop F is not just about Airbnb, or a city’s housing crisis, or the growing gap between those who have and those who do not. It speaks to the struggle of the law to keep up with the way technology is changing the economy and public policy. In a city increasingly uneasy with its relationship with the tech industry, it is a referendum on the effect of Silicon Valley on the average San Franciscan’s life.