Some 50 million Americans, about 30% of registered voters in the United States, are using electronic voting machines when they cast their ballot in this year's presidential election.
An election worker in Florida inspects electronic voting machines
More than half a dozen different models of machines have been introduced to avoid the kind of problems caused by antiquated punch-card systems that threw the US election into chaos and conflict in 2000.
Their proponents argue that they are simple to use and reliable, noting that they automatically log each vote. Critics attack the fact that many leave no paper trail to allow for a manual recount, and argue that they are too easily tampered with.
Four companies dominate the market for making voting machines: Diebold Election Systems, Election Systems and Software (ES&S), Sequoia Voting Systems and Hart InterCivic.
The systems all work similarly but have subtle differences.
- The AccuVote-TS
This is perhaps the most prevalent machine, and perhaps unsurprisingly coming from Diebold - a major maker of cash machines - the system works in a very similar fashion to an ATM.
Voters insert a smart card and make their choices by touching an area on the computer screen.
The votes are recorded on an internal electronic memory. The memory can be physically transmitted to election headquarters or transmitted via a computer network.
- The Avante Vote Trakker
This is one of the few versions that automatically produces a paper printout of the voters' choice.
Commonly Used Voting Machines
Avante Vote-Trakker EVC-308SPR
Diebold Accuvote TS v0.8
Danaher Controls, Inc.-Guardian Voting Systems ELECTronic 1242
Sequoia AVC Advantage
Sequoia AVC Edge
After inserting the smart card and voting, users can see a hard copy of their votes.
The paper is collected in a ballot box, and the votes are written onto an internal flash memory and a hard drive.
Later the collected votes are written on a CD-ROM to be tabulated at a central facility.
- The AVC Edge and the AVC Advantage
Both made by Sequoia, the Edge uses a touch screen while the Advantage uses a matrix of touch-sensitive switches to record votes.
With the Advantage, a poll worker must activate the machine and choose the ballot style. Votes are recorded on a battery-operated computer memory, RAM.
- The Hart InterCivic eSlate 3000
This system uses a select wheel to scroll through the choice of candidates.
The eSlate is connected to a booth which activates the machine for each voter and stores the votes.
Problems and praise
Opponents highlight the problems that have already occurred with the machines - pointing for instance to a congressional race in Ohio in which votes were incorrectly registered due to a problem with the memory cartridges.
At the same time however, Georgia's entirely electronic system appears to have few naysayers after two years in operation - although it is widely accepted that the presidential election will prove the greatest test.
The principal criticism remains the lack of paper audit trails. Nevada is the only state using machines which will provide voters with the kind of receipt which would, if necessary, allow for a manual recount.
But in order to accommodate some of the concerns, a number of states - including California - will give voters the opportunity to vote using electronic machines or a paper ballot form.