Optical scan voting system

An optical scan voting system is an electronic voting system and uses an optical scanner to read marked paper ballots and tally the results.


Marksense systemsEdit

While mark sense technology dates back to the 1930s and optical mark recognition dates to the 1950s, these technologies were first explored in the context of standardized tests such as college entrance exams. The first suggestion to use mark sense technology to count ballots came in 1953, but practical optical scanners did not emerge until the 1960s. The Norden Electronic Vote Tallying System was the first to be deployed, but it required the use of special ink to mark the ballot. The Votronic, from 1965, was the first optical mark vote tabulator able to sense marks made with a graphite pencil.[1]

The oldest optical-scan voting systems scan ballots using optical mark recognition scanners. Voters mark their choice in a voting response location, usually filling a rectangle, circle or oval, or by completing an arrow. Various mark-sense voting systems have used a variety of different approaches to determining what marks are counted as votes. Early systems, such as the Votronic, introduced in 1965, had a single photosensor per column of marks on the ballot. Most such tabulators, such as Optech, used analog comparators that counted all marks darker than a fixed threshold as being votes.[2]

The use of digital imaging technology to view the ballot does not necessarily imply more sophisticated mark recognition. For example, the Avante Vote-Trakker simply counts the number of dark and light pixels in each marking area to determine if the mark counts as a vote.[3] More sophisticated mark recognition algorithms are sensitive to the shape of the mark as well as the total overall darkness, as illustrated by the ES&S Model 100, introduced in the mid 1990s.[4]

An example of a ballot for a Diebold/Premier AV/OS scanner.

Electronic ballot markerEdit

An electronic ballot marker, the ExpressVote, made by Election Systems & Software. This prints a narrow ballot containing a summary of votes cast in both human-readable and bar code form.

An electronic ballot marker (EBM) or ballot marking device (BMD) is a device that can aid voters in marking paper ballots. Typical ballot markers include a touch screen and a variety of assistive devices to serve the needs of voters with disabilities.

In 1991, Julien Anno and others filed a patent application for a device resembling a modern electronic ballot marker, with an emphasis on multilingual ballot presentation, not accessibility.[5] The Jites and Digivote systems used in Belgium are similar to this, although they use magnetic stripe cards instead of bar codes to record the ballot.[6] Eugene Cummings filed a patent for an electronic ballot marker specifically designed as an accessible voting interface for optical-scan voting systems in 2003.[7] This machine, the Automark, saw widespread use in the United States.[8]

Digital pen voting systemsEdit

Digital pen voting systems use ballots on digital paper which is recognized by a small camera in the pen while it is marked by the voter.[9][10] The ballots are collected in a ballot box and the digital pen is returned to an election official for tabulation.

This technology was expected to be used in the 2008 Hamburg state elections, but eventually was decided against due to controversy surrounding the accuracy of voting tallies.[11][12]

The technology was first used by the town of Menstrie, Clackmannanshire Scotland in their 2006 local community council elections.[13]

Optical scan countingEdit

Scanner created image with black line implying votes for multiple candidates
Some States Check Election Machines' Counts by Hand


In an optical scan voting system, each voter's choices are marked on one or more pieces of paper, which then go through a scanner. The scanner creates an electronic image of each ballot, interprets it, creates a tally for each candidate, and usually stores the image for later review.

The voter may mark the paper directly, usually in a specific location for each candidate. The ballot can be immediately tabulated at polling stations allowing for voters to be notified by the voting system of voting errors such as an overvote and can prevent residual votes. One such method can display a digital image of the ballot being submitted and allows the voter to review how their ballots are being read.[14] This is known as a precinct-count voting system. Alternately the ballots can be collected in the polling station and tabulated later at a central facility, known as central-count voting system.

Or the voter may select choices on an electronic screen, which then prints the chosen names, usually with a bar code or QR code summarizing all choices, on a sheet of paper to put in the scanner.[15] This screen and printer is called an electronic ballot marker (EBM) or ballot marking device (BMD), and voters with disabilities can communicate with it by headphones, large buttons, sip and puff, or paddles, if they cannot interact with the screen or paper directly. Typically the ballot marking device does not store or tally votes. The paper it prints is the official ballot, put into a scanning system which counts the barcodes, or the printed names can be hand-counted, as a check on the machines.[16] Most voters do not look at the paper to ensure it reflects their choices, and when there is a mistake, 93% of voters do not report it to poll workers.[17]

Two companies, Hart and Clear Ballot, have scanners which count the printed names, which voters had a chance to check, rather than bar codes and QR codes, which voters are unable to check.[18]

Timing of optical scansEdit

The machines are faster than hand-counting, so are typically used the night after the election, to give quick results. The paper ballots and electronic memories still need to be stored, to check that the images are correct, and to be available for court challenges.

Errors in optical scansEdit

Scanners have a row of photo-sensors which the paper passes by, and they record light and dark pixels from the ballot. A black streak results when a scratch or paper dust causes a sensor to record black continuously.[19][20] A white streak can result when a sensor fails.[21] In the right place, such lines can indicate a vote for every candidate or no votes for anyone.

Software can miscount; if it miscounts drastically enough, people notice and check.

  • In a 2019 election in Northampton county, Pennsylvania, the software under-counted one candidate by 99%, reporting 164 votes, compared to 26,142 found in a subsequent hand-count, which changed the candidate's loss to a win.[22]
  • In a 2018 New York City election when the air was humid, ballots jammed in the scanner, or multiple ballots went through a scanner at once, hiding all but one.[23]
  • In a 2016 Maryland election, a comparison of two scanning systems on the same ballots revealed that (a) 1,972 ballot images were incorrectly left out of one system, (b) one system incorrectly ignored many votes for write-in candidates,[24] (c) shadows from paper folds were sometimes interpreted as names written in on the ballot, (d) the scanner sometimes pulled two ballots at once, scanning only the top one, (e) the ballot printers sometimes left off certain candidates, (f) voters often put a check or X instead of filling in an oval, which software has to adapt to, and (g) a scratch or dirt on a scanner sensor put a black line on many ballot images, causing the appearance of voting for more than the allowed number of candidates, so those votes were incorrectly ignored.[19][20]
  • In a 2004 Yakima, Washington, election 24 voters' choices on 4 races were ignored by a faulty scanner which created a white streak down the ballot.[21]
  • In a 2000 Bernalillo County (Albuquerque area), New Mexico, election, a programming error meant that straight-party votes on paper ballots were not counted for the individual candidates. The number of ballots was thus much larger than the number of votes in each contest. The software was fixed, and the ballots were re-scanned to get correct counts.[25][26]
  • Researchers find security flaws in all election computers, which let voters, staff members or outsiders disrupt or change results, often without detection.[27]

The scanner's tallying of ballots can be hacked by connecting a data cable to an election machine or by appropriate code on the memory cards used to transfer results from precinct machines to central count machines for reporting. Thousands of staff have access to the machines and cards before and during elections. Most machines and cards are unattended at polling places the night before every election. Successful attacks have been demonstrated by Harri Hursti[28] and the University of Connecticut.[29][30][31]

When a ballot marking device prints a bar code or QR code along with candidate names, the candidates are represented in the bar code or QR code as numbers, and the scanner counts those codes, not the names. If a bug or hack makes the numbering system in the ballot marking device not aligned with the numbering system in the scanner, votes will be tallied for the wrong candidates.[18] This numbering mismatch was suggested as early as 2005.[32] It has not been documented with ballot scans, but it has appeared with direct recording electronic machines.[33]

Some US states check a small number of places by hand-counting or use of machines independent of the original election machines.[34]

Besides software problems, paper ballots are subject to traditional risks, such as ballot box stuffing, ballot destruction and vote buying. These have traditional prevention measures, Some suggest many of these well-known vulnerabilities can be effectively mitigated. Ballot stuffing may be resolved with incorporation of randomly generated ballot identifier for each paper ballot and capturing digital ballot images of scanned ballots as electronic audit.[35] Tabulation fraud and wholesale tampering can also be prevented by End-to-end auditable voting systems[36] such as Scantegrity.


Recounting optical-scan ballots by hand in Minnesota.

An advantage of these systems is that the voters don't have to learn to use a voting machine. Physically able voters can simply use pen and paper to mark their intent. Some disabled voters could use a machine to print a voted ballot, which can then be fed into the optical scanner along with all the other ballots, thus preserving the secrecy of their ballot.

Optical scan voting systems can allow for manual recounting of ballots and random auditing of the election equipment that reports the results to election officials. Statistically relevant auditing can serve as a tool to detect or deter malfunction or fraud. In the instance where a candidate is entitled to a recount, a full hand recount of paper ballots can determine the accurate, or final results. Officials responsible for maintaining the veracity and accuracy of elections such as election commissioners or county auditors, can randomly select a voting block such as a precinct to verify the optical scanning voting system tabulation and report is accurate by doing a hand count against the machine's results. By performing such an audit, election officials can confirm the system is in good standing. Or, if an error in the counting is discovered during a random audit of the machine(s), a full recount can be conducted, and the system evaluated for the source of failure or fraud.

An advantage compared to DRE voting machines is that even if the optical scanner fails, voters can still fill out their paper ballot, and leave it to be scanned when the machine is fixed or replaced with a spare. This also allow many more people to simultaneously vote than would be the case with fully computerized voting.

Using more than 80,000 optical scanners during its last two elections (2010 and 2013), the Philippines has reduced the time to process votes and announce results. The Philippine elections constitute the largest deployment of optical scanners in the world.

Recreated ballotsEdit

Recreated ballots are paper[37] or electronic[38] ballots created by election staff when originals cannot be counted for some reason. They usually apply to optical scan elections, not hand-counting. Reasons include tears, water damage and folds which prevent feeding through scanners. Reasons also include voters selecting candidates by circling them or other marks, when machines are only programmed to tally specific marks in front of the candidate's name.[39] As many as 8% of ballots in an election may be recreated.[38]

Recreated ballots are sometimes called "reconstructed ballots."[37] The term "duplicate ballot" sometimes refers to these recreated ballots,[40] and sometimes to extra ballots erroneously given to or received from a voter.[41]

Because of its potential for fraud, recreation of ballots is usually done by teams of two people working together[42] or closely observed by bipartisan teams.[37] The security of a team process can be undermined by having one person read to the other, so only one looks at the original votes and one looks at the recreated votes, or by having the team members appointed by a single official.[43]

When auditing an election, audits need to be done with the original ballots, not the recreated ones.

Cost of scanning systemsEdit

If most voters mark their own paper ballots and one marking device is available at each polling place for voters with disabilities, Georgia's total cost of machines and maintenance for 10 years, starting 2020, has been estimated at $12 per voter ($84 million total). Pre-printed ballots for voters to mark would cost $4 to $20 per voter ($113 million to $224 million total machines, maintenance and printing). The low estimate includes $0.40 to print each ballot, and more than enough ballots for historic turnout levels. the high estimate includes $0.55 to print each ballot, and enough ballots for every registered voter, including three ballots (of different parties) for each registered voter in primary elections with historically low turnout.[44][45] The estimate is $29 per voter ($203 million total) if all voters use ballot marking devices, including $0.10 per ballot for paper.

The capital cost of machines in 2019 in Pennsylvania is $11 per voter if most voters mark their own paper ballots and a marking device is available at each polling place for voters with disabilities, compared to $23 per voter if all voters use ballot marking devices.[46] This cost does not include printing ballots.

New York has an undated comparison of capital costs and a system where all voters use ballot marking devices costing over twice as much as a system where most do not. The authors say extra machine maintenance would exacerbate that difference, and printing cost would be comparable in both approaches.[47] Their assumption of equal printing costs differs from the Georgia estimates of $0.40 or $0.50 to print a ballot in advance, and $0.10 to print it in a ballot marking device.[44]

Machine manufacturersEdit

See alsoEdit


  1. ^ Douglas W. Jones, On Optical Mark-Sense Scanning, Towards Trustworthy Elections, Lecture Notes on Computer Science Vol. 60, Springer, 2010. (author's copy)
  2. ^ Gerald Holzer, Norman Walker and Harry Wilcox, Vote Tallying Machine, U.S. patent 3,218,439, Nov. 16, 1965.
  3. ^ Kevin Kwong-Tai Chung, Victor Jun Dong and Xaoming Shi, Electronic Voting Method for Optically Scanned Ballot, U.S. Patent 7,077,313, Jul. 18, 2006.
  4. ^ Steve Bolton, Tim Cordes and Herb Deutsch, Method of Analyzing Marks Made on a Response Sheet, U.S. Patent 6,854,644, Feb. 15, 2005.
  5. ^ Julien Anno, Russel Lewis, and Dale Cone, Method and System for Autonated Voting, U.S. Patent 5,189,288, issued Feb. 23, 1993.
  6. ^ Expert Visit on New Voting Technologies, 8 October 2006 Local Elections, Kingdom of Belgium, OSCE Office for Democratic Institutions and Human Rights, Nov. 22, 2006.
  7. ^ Eugene Cummings, Ballot Marking System and Apparatus, U.S. Patent 7,080,779, issued Jul. 25, 2006.
  8. ^ Douglas W. Jones and Barbara Simons, Broken Ballots, CSLI Publications, 2012; see Section 5.5, pages 111-115, and Section 9.3, pages 218-221.
  9. ^ New Generation of Voting Machines in Germany Archived 2007-09-29 at the Wayback Machine
  10. ^ Ulrich Wienser, Hacking the Electoral Law, Page 37ff
  11. ^ "Politik & Verwaltung". hamburg.de. Retrieved 15 May 2016.
  12. ^ Heise.de: Aus für den digitalen Wahlstift (German)
  13. ^ Electronic voting 'world first', BBC News September 27, 2006
  14. ^ "Precinct-Based Optical". Avante International Technology, Inc. Retrieved 15 May 2016.
  15. ^ "Ballot Marking Devices". Verified Voting. Retrieved 2020-02-28.
  16. ^ Cohn, Jennifer (2018-05-05). "What is the latest threat to democracy?". Medium. Retrieved 2020-02-28.
  17. ^ Bernhard, Matthew, Allison McDonald, Henry Meng, Jensen Hwa, Nakul Bajaj, Kevin Chang, J. Alex Halderman (2019-12-28). "Can Voters Detect Malicious Manipulation of Ballot Marking Devices?" (PDF). Halderman. Retrieved 2020-02-28.
  18. ^ a b Perez, Edward, Joy London, Gregory Miller (March 2019). "Georgia State Election Technology Acquisition, Assessing Recent Legislation in Light of Planned Procurement" (PDF). OSET Institute. Retrieved 2020-03-05.
  19. ^ a b Walker, Natasha (2017-02-13). "2016 Post-Election Audits in Maryland" (PDF). Elections Advisory Commission. Retrieved 2020-02-27.
  20. ^ a b Ryan, Tom and Benny White (2016-11-30). "Transcript of Email on Ballot Images" (PDF). Pima County, AZ. Retrieved 2020-02-15.
  21. ^ a b Gideon, John (2005-07-05). "Hart InterCivic Optical-Scan Has A Weak Spot". www.votersunite.org. Retrieved 2020-02-15.
  22. ^ Corasaniti, Nick (2019-11-30). "A Pennsylvania County's Election Day Nightmare Underscores Voting Machine Concerns". The New York Times. ISSN 0362-4331. Retrieved 2020-02-15.
  23. ^ MacDougall, Ian (2018-11-07). "What Went Wrong at New York City Polling Places? It Was Something in the Air. Literally". ProPublica. Retrieved 2020-02-18.
  24. ^ Lamone, Linda (2016-12-22). "Joint Chairman's Report on the 2016 Post-Election Tabulation Audit" (PDF). Maryland State Board of Elections. Retrieved 2020-02-15.
  25. ^ Gruley, Bryan, and Chip Cummins (2000-12-16). "Election Day Became a Nightmare, As Usual, for Bernalillo County". Wall Street Journal. ISSN 0099-9660. Retrieved 2020-03-11.
  26. ^ Baker, Deborah (2004-10-31). "ABQjournal: Contentious 2000 Election Closest in N.M. History". Albuquerque Journal. Retrieved 2020-03-11.
  27. ^ Blaze, Matt, Harri Hursti , Margaret Macalpine, Mary Hanley, Jeff Moss, Rachel Wehr, Kendal L Spencer, Christopher Ferris (2019-09-26). "DEF CON 27 Voting Machine Hacking Village" (PDF). Defcon. Retrieved 2020-03-11.
  28. ^ "VoteTrustUSA - Florida: The Harri Hursti Hack and its Importance to our Nation". Retrieved 15 May 2016.
  29. ^ A. Kiayias, L. Michel, A. Russell, A. A. Shvartsman, with the assistance of M. Korman, A. See, N. Shashidhar, D. Walluck. Security Assessment of the Diebold Optical Scan Voting Terminal (UConn VoTeR Center and Department of Computer Science and Engineering, University of Connecticut, October 30, 2006)
  30. ^ "Reports". 10 May 2008. Archived from the original on 10 May 2008. Retrieved 14 November 2018.
  31. ^ "Center for Voting Technology Research". 31 May 2018. Archived from the original on 31 May 2018. Retrieved 14 November 2018.
  32. ^ EXAMPLE ATTACK DOCUMENTATION: Optical Scan Configuration File, Douglas W. Jones Sept 15, 2005
  33. ^ Buell, Duncan (2018-12-23). Analysis of the Election Data from the 6 November 2018 General Election in South Carolina (PDF). League of Women Voters of South Carolina (Report). Retrieved 2020-02-05.
  34. ^ "State Audit Laws". Verified Voting. 2017-02-10. Retrieved 2018-04-02.
  35. ^ Tabulation of Paper Ballots using Optical Scanning Electronic and Tabulation of Direct Recording Electronic with Voter Verified Paper Ballots, AVANTE International Technology, Inc. March 1, 2007
  36. ^ Mahoney, Matt (September–October 2008), "Flawless Vote Counts: Cryptography lets voters confirm that their ballots were tallied correctly", Technology Review
  37. ^ a b c "observers from both political parties there... ballots have to be recreated in every election for a number of reasons, ranging from damaged mail-in ballots, to early voters who use pencils which can’t be read by ballot tabulators." Jordan, Ben (2018-11-07). "MKE Election Commission responds to criticism". WTMJ TV Milwaukee. Retrieved 2020-05-17.
  38. ^ a b "With the new digital procedure, staff will be able to fix whatever race couldn’t be counted, instead of duplicating a voter’s entire ballot." White, Rebecca (2019-11-18). "One Washington County Plans to Speed Vote Counting with Tech". Government Technology. Retrieved 2020-05-17.
  39. ^ Writer, Steve Miller, Journal Staff (2006-11-07). "Oddly marked ovals bane of poll workers' day". Rapid City Journal. Retrieved 2020-05-17.
  40. ^ Black, Eric (2008-12-17). "Recount's next big issue: duplicate ballots". MinnPost. Retrieved 2020-05-17.
  41. ^ Tomasic, Megan (2020-05-14). "Some Allegheny County voters received duplicate mail-in ballots due to system glitch". Tribune Review. Retrieved 2020-05-17.
  42. ^ Duplicate ballot procedures in Ventura County, CA https://recorder.countyofventura.org/wp-content/uploads/2018/05/BALLOT-DUPLICATION-PROCESS-FACTS-2-Final-1.pdf
  43. ^ Duplicate ballot procedures in Michigan https://www.michigan.gov/documents/sos/XII_Precinct_Canvass_-_Closing_the_Polls_266013_7.pdf
  44. ^ a b Perez, Edward, and Gregory Miller (March 2019). "Georgia State Election Technology Acquisition, A Reality Check". OSET Institute. Retrieved 2020-03-06.
  45. ^ Fowler, Stephen. "Here's What Vendors Say It Would Cost To Replace Georgia's Voting System". Georgia Public Broadcasting. Retrieved 2020-02-28.
  46. ^ Deluzio, Christopher, Kevin Skoglund (2020-02-28). "Pennsylvania Counties' New Voting Systems Selections: An Analysis" (PDF). University of Pittsburgh. Retrieved 2020-02-28.
  47. ^ "NYVV - Paper Ballots Costs". www.nyvv.org. Retrieved 2020-02-28.