I've been thinking about various scenarios where hypothetically one might be able to hack a US election. In the 2016 election, it seems to me that Trump won because of slim majorities in Wisconsin, Michigan, and Pennsylvania. Looking more closely at county-by-county results, larger turn out in big cities like Milwaukee, Detroit, Pittsburgh, and Philadelphia could have handed the election instead to Clinton. Okay, so what if...

What if I were one of these mythical Russian hackers, and I had access to the state voter registration rolls in Wisconsin, Michigan, and Pennsylvania. To cause mischief I randomly deleted 10% of the names of people living in the big cities. Would these deleted voters have trouble voting on election day? Could they cast provisional ballots? How would the state and county election boards detect such a hack? Could such a hack explain, for example, low voter turnout in Milwaukee?

  • One would expect someone is trending voter numbers in most districts.
    – user9389
    Commented Dec 1, 2016 at 19:46
  • I have looked at the numbers, and turnout in Milwaukee for example was down 18% compared with 2012. The explanations proposed, however, are usually voter disinterest and stricter voter id laws. Commented Dec 1, 2016 at 19:50
  • I was thinking of registered more than participants. Messing with participants is traditionally the work of thugs not hackers.
    – user9389
    Commented Dec 1, 2016 at 20:18
  • Simply way to detect the hack - all this data gets backed up somewhere. If you compare old vs new data and suddenly see a 10% unexplained drop you know something went wrong. Commented Dec 1, 2016 at 20:34
  • Okay, good, so as a hacker, instead of deleting 10% of the names, I should replace them with made up names or scramble names and addresses. Commented Dec 1, 2016 at 20:57

2 Answers 2


Deleting people from rolls would be unwise, since it is easier to detect when the people affected go to vote and detect they are not allowed.

In a busy precint, removing one of each ten means that, while the first person affected is still trying to solve it/argue with election officials, the next one who has been deleted will arrive and join in... in few time you will have an actual crowd of angry people at most of the precincts, getting nationwide attention. If you are doing something criminal, usually you do not want to attract nationwide attention1.

And yes, in Michigan you could still vote with a provisional ballot.

A different tactic would be adding to the rolls people who are not allowed to vote, or even unexistent people (so people with fake IDs would vote twice or more). Detecting these is more of a problem, since it does not involve innocent people. Still, it is a significant risk due to:

  • You need a lot of people to effectively go and knowingly vote illegally, risking someone reporting the information to the authorities.

  • Voter rolls are to be verified and are. Anyone could check why so many people share the same address, or why some guys have an address in a corn field. Of course, the more voters you add, the more risk.

And those cases are detected. Although I would say that this case was more one of registration workers trying to "meet objectives" with made up registers than of attemptin at falsifying the election2, it was indeed detected and punished.

Third, and more subtle, could be changing the census data in order to get a red or blue state more electors due to a higher population. This would be somewhat related to option #2, differing in that:

  • If you are in the right position you need less people to take part (less risk of people talking out), but

  • You need to fake a LOT more of data, increasing the risk of the wrong data being detected.

For all of these, it has to be considered that:

a) Your manipulations are likely to show inconsistencies with other data (e.g., way more voters enrolled that the census numbers would predict).

b) You will not know beforehand if the risk is worth it. If someone knew a year before that Michigan race was going to be that close and would be the one that decided the POTUS, maybe he could consider the risk of being caught modifying a few hundreds or thousands of votes justified by the possibility of changing the government. But if he does not know if those hundred or thousands are going to be decissive or just "noise", there is way less incentive to attempt fraud.

1At least I don't want to. YMMV.

2Unless someone planned to show at the poll station with a "Mickey Mouse" ID.

  • As a mythical Russian hacker, my goal might not be to influence the election, just to cause mischief and produce loss of faith in the process and validity of the results. I gather from reading the papers that many people were turned away from the polls in Milwaukee, chicagotribune.com/news/nationworld/midwest/…. Commented Dec 1, 2016 at 18:38
  • Do you know if you could vote in Pennsylvania or Wisconsin with a provisional ballot if your name had been cleansed from the rolls? Commented Dec 1, 2016 at 19:45

I am going to add to SJuan's answer above rather than rehashing the fine points he/she made.

Would these deleted voters have trouble voting on election day?

No, Answered by SJuan

Could they cast provisional ballots?

Yes, Answered by SJuan

How would the state and county election boards detect such a hack?

Through post election audits.

A number of states have enacted requirements for mandatory manual audits (in randomly selected precincts) of the voter-verified paper records produced by the voting systems in use in those states. These audits are designed to verify that the electronic voting systems (either DRE voting machines or optical scan voting systems) are accurately recording and counting the votes. In the randomly-selected precincts, a hand count of the voter-verified paper records is compared to the totals reported by the electronic voting system.

There are also other technology checks to gauge tampering. These checks would cover penetration testing of voter registration systems and other related voting processes, like systemically turning away 10% of the electorate, for example. For more about post-election audits, go here

Could such a hack explain, for example, low voter turnout in Milwaukee?

There has been no credible evidence of a hack as of Dec 1, 2016 presented in a mainstream publication.

  • Not sure what you have in mind with post election audits. Person X is not on the rolls. Person X was turned away from the polls and did not vote. There is then not necessarily any record in the election data that one should worry about Person X, unless they were able to file a provisional ballot. Commented Dec 1, 2016 at 18:35
  • @user2309840 see revised answer to get you to your hypothetical
    – user9790
    Commented Dec 1, 2016 at 18:54
  • Sorry, I see no discussion of my hypothetical in your link. Can you explain? Commented Dec 1, 2016 at 19:43
  • @user2309840 Sure, technology penetration tests would be conducted not just on voting systems but registration systems. And trend analysis would be done on the registration rolls for the weeks prior (week over week) and years prior (year over year). A systemic change would have to be explainable.
    – user9790
    Commented Dec 1, 2016 at 20:53
  • Re "There has been no...": The OP asked if a theoretical attack could explain a specific event. The OP did not ask whether the popular press supported such a theory. Non-sequiter.
    – agc
    Commented Dec 3, 2016 at 6:13

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