This story is part of, CNET's coverage of the voting in November and its aftermath.
Politicians are exploiting intimate details about your life to win elections and influence policy.
Your voter history and party registration are public records that are easy to access. Your phone number, home address, salary and debt history, and how you feel about controversial issues like gun control, can be purchased cheaply. Everything you post on social media is easy to scrape and collect. And mobile apps built by the Trump and Biden presidential campaigns give them unprecedented access to your device's location history, and a whole lot more.
Campaigns use this data to raise money, find and persuade new voters, and compel their base to vote. Our phones give them a vast and high-quality amount of data, said CBS News political analyst Leslie Sanchez.
"What's truly amazing about [the campaigns] is they are very open, in some ways bragging, about the fact that they are harvesting tremendous amounts of data from people's cellphones, from people who are opting in to be part of the campaign," she said. "With that cellphone number, you can unlock a tremendous amount of information about actual voting behavior or buying behavior."
Politicians use your personal data to persuade you to donate money, keep you engaged during the campaign, and get out the vote on Election Day. They do this by creating finely tuned, provocative messages targeted at specific audiences on broadcast and print media, and sites like Google, Facebook, and Twitter.
"Campaigns are using all that personal technology and insights about voters to engage and activate them and vote or act in a certain way, in a certain part of the country, for their election," said Sanchez."
Unlocking your personal data: How it works
Technology helps campaigns scale voter turnout initiatives, but data-driven campaigns are as old as ballot boxes. Modern get-out-the-vote efforts date back to the 1970s, said Paul Westcott, vice president of L2 Political, a nonpartisan data provider. His firm creates voter mobilization tools for campaigns by bundling publicly available information with proprietary data.
"You had phone banks, you had door-knocking, people going door to door, you had lawn signs, print, radio and all the traditional types of broadcast television and early cable TV ads," said Westcott. "Now there's a world of devices and a world of ways to get media, and campaigns just like those on the consumer side are chasing those around and bringing along their data with them."
Modern campaigns rely on three primary sources of political data.
The first is your voter file. In most states, your voter registration details are available through the Secretary of State's office, including your home address, party registration, and voting history. This information can provide campaign strategists with enough information to target you with broad messages.
The real power of your voter file is unlocked when it's combined with data that campaigns purchase from commercial vendors. Many credit monitoring and advertising agencies gather and sell information about consumers, including your income, how you spend money, your family members and other intimate details. Political data miners and consultants often sell information about your demographics and psychographic details, and companies like Morning Consult conduct targeted surveys on how voters feel about specific issues.
Campaigns also gather a great deal of information themselves. You provide important information to campaigns when you tell door-knocking canvassers how you feel about issues, or share your email address and phone number with rally organizers. This information sends a number of important signals to campaigns, including info about what messages you're receptive to, who you will vote for or even if you're planning to vote at all.
The Trump and Biden apps provide the 2020 campaigns with a "goldmine of personal data," including not just your location history, but also the make and model of your device, your device's unique ID number, and contact list. How long they keep that data depends on the campaign. The Trump campaign told CNET that its data retention policies are defined by the end-user license agreement in the application, which does not provide detailed information about who owns your data or for how long. A spokesperson for the Biden campaign explained that "when the campaign is over, we'll delete our data," though the Democratic party is building a data exchange platform intended to make sharing voter information easy. The Republican party built a similar platform prior to the 2016 election.
Tech is not a magic bullet
But after campaigns ingest this information, then what happens? First, they append it to the other information they have about you, then adjust their messaging accordingly, said CBS News Senior Manager of Elections Kabir Khanna.
"One common technique is A/B testing where they have slightly different versions of the same [ad] video and deployed them to random samples of their Facebook users," said Khanna "One group saw Version A and one group saw Version B … and [campaigns] were then able to test out which version was more effective."
Khanna, however, questions the efficacy of big data as a tool for voter engagement by political campaigns, and warns against using a technology "magic bullet." Data science, he said, is a vocation that requires significant skill and training. Some campaigns do hire experts, but many cannot afford to hire and train armies of digital operatives.
All data -- not just the personal information used in politics -- can be faulty or only partially accurate, Khanna said. "Algorithms are coded by humans, and humans make mistakes ... campaigns go to war with the data they have, not the data they would like to have. So often what they have is kind of a rough guesstimate of details about you, your background, your political persuasion, and what you might do in the next election. But it's by no means perfect."