June 15, 2024

When the optical scanners jam up, what then?

In the November 2018 election, many optical-scan voting machines in New York experienced problems with paper jams, caused by the rainy weather and excessive humidity.

Also, this was the first time New York used a 2-page ballot that the voter had to separate at the perforations.  This doubled the number of sheets of paper that the optical scanners had to process.

These two factors caused long lines, and voter frustration, at some polling places.  At some polling places, there were not adequate “emergency ballot boxes” for deposit of not-yet-scanned paper ballots.

New York, like many other states, uses a robust, trustworthy, and reliable means of balloting:  optical-scan paper ballots, hand-marked by the voters (except for those voters who choose to use a ballot-marking device), which the voter deposits directly into an optical scanner.  That is, “precinct-count optical scan” (PCOS).

No voting method is perfect, but PCOS is less imperfect than other methods.  Here are some important principles of precinct-count optical scan:

  1. Feedback: if the voter inadvertently overvotes the ballot (marks too many bubbles in the same contest), the scanner can alert the voter to this problem, giving the voter the chance to correct it by filling in a fresh ballot.
  2. Immediate count:  vote totals are reported as soon as the polls close.  Unofficial (but informative) precinct totals can be reported immediately to the county, to the news media, and to members of the public present at the polling place.  Also, there’s at least one count of the votes before any transportation or handling of ballot boxes.  The paper ballots are legally the ballot of record for recounts, with random audits of paper ballots necessary to detect and deter cheating via hacking of optical scanner software.  But if there is interference with the paper ballots in the chain of custody between the precinct and the audit or recount, the in-the-precinct totals are at least evidence that an investigator or court of law might find useful.
  3. Robustness:  if the power fails, or the optical scanner fails for some other reason, voters can still hand-mark their optical-scan ballots, and deposit them into a ballot box for later counting.

You might notice that “deposit into a ballot box for later counting“ conflicts with ”feedback” and “immediate count.”  What should we do about that?

I have consulted with several experts in election verification, and here are the consensus recommendations:

If the optical scanner fails for some reason, and cannot immediately be put back into operation, then pollworkers should promptly switch to the mode of depositing ballots in ballot boxes to be counted later.  This will minimize the chance of long lines at the polling places, and therefore will minimize the number of voters who are discouraged from voting by long lines.  Election administrators should make sure every polling place is equipped with the appropriate ballot boxes for deposit of central-count ballots, if high-capacity bins are not already built into the PCOS itself.

For the duration of the outage, voters will lose the advantage of overvote detection/correction.  Compared to disenfranchising voters by making stand in line for hours until the voting machines are fixed, this is the lesser of two evils–especially since overvotes are quite rare anyway (and all those voters that use mail-in ballots don’t get feedback either about their overvotes).

Still, I believe these recommendations are consistent with New York’s policies, and I believe that polling places in New York followed these procedures.  And yet there were news articles about the problem.  What went wrong, and what could be improved?


Professor Charles Stewart (MIT) writes, “The problem I saw reported was what happened when precincts transitioned to putting the ballots in the “emergency” ballot box.  Many poll workers weren’t confident about what to do.  They were frazzled.  That was picked up by the voters, who reacted suspiciously. … So, it seems to me that the real issue was not the procedure, but the training around the procedure.  We all know that you learn emergency procedures through drill, drill, drill, and I suspect that poll worker training will never be long enough to do a good job of making all poll workers confident enough to just slide into emergency mode and pull it off without a hitch.”

Early voting as a form of pollworker training.

Jennifer Morrell (election consultant and former Colorado election official) writes,  “The poll worker training we conducted in Arapahoe County, Colorado was almost 40 hours for the supervisor of each polling location and slightly less for the other poll workers. … One entire day was spent in a mock election ‘lab’ where the poll workers were faced with the worst case scenarios my team could concoct. Practicing is everything! … All of this is feasible because of the 400,000+ registered voters in that county, less than 10% opted to vote in person at one of 26 voter service and polling centers. Staffing, equipping, and adequately training poll workers can be done successfully when you can focus on just a few dozen locations versus hundreds of locations.  Those same poll workers then have almost 2 weeks of early voting where turnout is light to practice, work out any kinks, make sure all the equipment is there and functioning properly, etc. …  The election model really does make a difference.”

Precinct count without (immediate) optical scan.

Professor Doug Jones (U. of Iowa) writes,  “At least in Iowa, the precinct workers …  count the contents of the emergency ballot bin immediately after the polls close, either by inserting the ballots in the scanner (assuming it has been made operational after a temporary failure) or by hand counting them.  As a result, the totals reported from the precinct always include all non-provisional ballots cast at that precinct.  During the count of ballots from the emergency ballot box (and also, during the central count of absentee ballots), the scanner is always set to sort out and not count ballots that scan as blank or contain overvotes.  These ballots are always subject to human interpretation, since most overvoted ballots and many apparently blank ballots contain clear indications of voter intent.”

(Indeed, New York’s procedures are similar; see state statute 9-110. Canvass; election day paper ballots that have not been scanned; method of.)

Quality of the paper.

Jennifer Morrell writes, “Paper thickness, weight, and humidity are critically important! So is the type of ink used [by ballot-on-demand printers] to print the ballots and knowing if there is any type of coating or finishing spray used. Sticking to the same paper manufacturer throughout the print run makes a difference. So does the way the paper is cut – blade vs laser cut. Also, scanners have to be cleaned on a regular basis (after so many pieces of paper scanned).”

So therefore, choose your printing company after a thorough RFI/RFP process to make sure they have knowledge and expertise with ballots.   Such a company will make sure to use paper that satisfies the specs provided by the voting-machine vendor, and use the same paper for the entire print run. (But as others have pointed out, don’t fall into the trap of sole-sourcing your paper and paying too much.)

What if only some of the machines are working?

The experience in New York raises this question:  What if at least some scanners are operational in the precinct, but the lines at the scanner are very long anyway?  (This might be because there are just too many sheets of paper to be scanned, as a product of voter turnout and ballot length.)   If the lines at the scanner are long, then the pollworkers at the check-in station (pollbooks) are probably holding voters back because there’s not place for them to mark their ballots, and so on.

This suggests that a reasonable policy might be, If the optical scanners cannot handle the volume of ballots for any reason, then pollworkers should promptly switch to the mode of depositing ballots in ballot boxes to be counted later. 

I’ll be that is not the current policy in New York, or Iowa!

Experience is a great teacher.

New York’s 2010 transition from lever machines to optical scanners was carefully planned, and overall the scanners worked well between 2010 and 2016.  This year’s problem with paper jams may have surprised New York’s election administrators, but I’m willing to bet that the next time it rains on election day, they’ll make things go more smoothly.


  1. Do optical scanners damage the secrecy of the ballot? I voted in New York City. The stub above the perforation was given my initials. The stubs were numbered sequentially and the ballots accumulated in the scanner in an order that approximated the sequential numbering of the stubs. I suspect each perforation tear pattern is unique. Voting took place in a school cafeteria which was loaded with security cameras that could have recorded the order voters approached the machine.

    The scanner jammed for the voter that followed me. If the scanner was not returned to service then my vote would have obviously been at the top of the pile and the camera would show I was the last successful voter.