Private companies have collected millions of political profiles of Americans.

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."

The slideshow was online until last week, when the company removed it after we asked for comment. (Here is the full slideshow.) Rich Masterson, CampaignGrid's chairman, wrote in an email that the slideshow was posted in error: "It was an unapproved version of a sales deck that was posted by an intern who no longer works for the company."

CampaignGrid does indeed collect 18 different "attributes" for every voter, Masterson told ProPublica, including age, gender, political donations, and more. Campaigns use this data to tailor the online ads you see.

Online targeting has taken off this campaign season. ProPublica has identified seven companies that advertise the ability to help campaigns target specific voters online. Among them is Experian, the credit reporting company. Datalogix, a company that works with Facebook to track users' buying patterns, is also involved. (Here are marketing materials and comment from the seven companies). CampaignGrid and a few, similar firms have been profiled for their innovative approaches. Yet the scale of the targeting and the number of companies involved has received little notice.

Few of the companies involved in the targeting talk about it publicly. But CampaignGrid, which works with Republicans, and a similar, Democratic firm, Precision Network, told ProPublica they have political information on 150 million American Internet users, or roughly 80 percent of the nation's registered voters.

The information — stripped of your name or address — is connected to your computer via a cookie. Targeting firms say replacing your name with an ID number keeps the process anonymous and protects users' privacy.

But privacy experts say that assembling information about Internet users' political behavior can be problematic even if voters' names aren't attached.

"A lot of people would consider their political identity more private than lots of information," said William McGeveran, a data privacy expert at the University of Minnesota Law School. "We make more rules about medical privacy. We make more rules about financial privacy. So if you think private political beliefs are in that category, maybe you're concerned about having them treated like your favorite brand of toothpaste."

Google has stayed away from this kind of targeting. It classifies political beliefs as "sensitive personal information," in the same category as medical information and religious beliefs.
But other big players have embraced the "political cookie," as one company branded it.

As we reported in June, Yahoo and Microsoft sell access to your registration information for political targeting. That's one way CampaignGrid and other companies find you online. Political targeting firms say they also work with other websites, but would not name them.

While campaigns and the firms working with them can buy reams of data about voters, voters have been left mostly in the dark.

Many online ad companies mark targeted ads with a small blue triangle symbol, or the phrase "Ad Choices," and offer surfers a chance to opt out. But even if web users know what the triangle means, they get no information about how or why they were targeted.

"Consumers don't really understand what's going on and haven't given their permission," says Joseph Turow, a digital marketing and privacy expert at the University of Pennsylvania's Annenberg School for Communication.

There are few legal regulations governing how online targeting works, or what notification consumers must receive.

Online advertising experts point out that individual voting records are public information and have long been used to target voters through direct mail. And targeting companies say they are offering a valuable service. Instead of seeing random ads, users get to see ads from candidates they might actually want to support.http://www.propublica.org/article/how-companies-have-assembled-political-profiles-for-millions-of-internet-us