How Companies Have Assembled Political Profiles for Millions of Internet Users

by Lois Beckett
ProPublica, Oct. 22, 2012, 2:07 p.m.

If you're a registered voter and surf the web, one of the sites you visit has almost certainly placed a tiny piece of data on your computer flagging your political preferences. That piece of data, called a cookie, marks you as a Democrat or Republican, when you last voted, and what contributions you've made. It also can include factors like your estimated income, what you do for a living, and what you've bought at the local mall.

Across the country, companies are using cookies to tailor the political ads you see online. One of the firms is CampaignGrid, which boasted in a recent slideshow, "Internet Users are No Longer Anonymous." The slideshow includes an image of the famous New Yorker cartoon from 1993: "On the Internet, nobody knows you're a dog." Next to it, CampaignGrid lists what it can now know about an Internet user: "Lives in Pennsylvania's 13th Congressional District, 19002 zip code, Registered primary voting Republican, High net worth household, Age 50-54, Teenagers in the home, Technology professional, Interested in politics, Shopping for a car, Planning a vacation in Puerto Rico."