All levels of government share responsibility in the U.S. election process. At the federal level, Congress has authority under the Constitution to regulate presidential and congressional elections and to enforce prohibitions against specific discriminatory practices in all federal, state, and local elections. Congress has passed legislation that addresses voter registration, absentee voting, accessibility provisions for the elderly and handicapped, and prohibitions against discriminatory practices. At the state level, individual states are responsible for the administration of both federal elections and their own elections. States regulate the election process, including, for example, the adoption of voluntary voting system guidelines, the state certification and acceptance testing of voting systems, ballot access, registration procedures, absentee voting requirements, the establishment of voting places, the provision of election day workers, and the counting and certification of the vote. In total, the U.S. election process can be seen as an assemblage of 55 distinct election systems—those of the 50 states, the District of Columbia, and the 4 U.S. territories. Further, although election policy and procedures are legislated primarily at the state level, states typically have decentralized voting processes, so that the details of administering elections are carried out at the city or county levels, and voting is done at the local level. As we reported in 2001, local election jurisdictions number more than 10,000, and their sizes vary enormously—from a rural county with about 200 voters to a large urban county, such as Los Angeles County, where the total number of registered voters for the 2000 elections exceeded the registered voter totals in 41 states. Administering an election is a year-round process involving the following stages: Voter registration. Local election officials register eligible voters and maintain voter registration lists. This includes updating registrants’ information and deleting the names of registrants who are no longer eligible to vote. Absentee and early voting. Election officials design ballots and other systems to permit eligible people to vote in person or by mail before election day. Election officials also educate voters on how to vote by these methods. Election administration and vote casting. Election officials prepare for an election by arranging for polling places, recruiting and training poll workers, designing ballots, and preparing and testing voting equipment for use in casting and tabulating votes. Election day activities include opening and closing polling places and assisting voters in casting votes. Vote counting and certification. Election officials tabulate the cast ballots, determine whether and how to count ballots that cannot be read by the vote counting equipment, certify the final vote counts, and perform recounts, if required. As shown in figure 1, each stage of an election involves people, processes, and technology. Electronic voting systems hold promise for improving the efficiency and accuracy of the election process by automating a manual process, providing flexibility for accommodating voters with special needs, and implementing controls to avoid errors by voters and election workers. In the United States today, most votes are cast and counted by one of two types of electronic voting systems: optical scan systems and direct recording electronic (DRE) systems. Such systems include the hardware, software, and firmware used to define ballots, cast and count votes, report or display election results, and maintain and produce audit trail information—as well as the documentation required to program, control, and support the equipment. A description of both technologies follows. Optical Scan Systems. Optical scan voting systems use electronic technology to tabulate paper ballots. Although optical scan technology has been in use for decades for such tasks as scoring standardized tests, it was not applied to voting until the 1980s. According to Election Data Services, Inc., a firm specializing in election data statistics, about 31 percent of registered voters voted on optical scan systems in the 2000 election, and about 35 percent of registered voters voted on optical scan systems in the 2004 election. An optical scan system is made up of computer-readable paper ballots, appropriate marking devices, privacy booths, and a computerized tabulation device. The ballot, which can be of various sizes, lists the names of the candidates and the issues. Voters record their choices using an appropriate writing instrument to fill in boxes or ovals, or to complete an arrow next to a candidate’s name or the issue. In some states, the ballot may include a space for write-ins to be entered directly on the ballot. Optical scan ballots are tabulated by optical-mark-recognition equipment (see fig. 2), which counts the ballots by sensing or reading the marks on the ballot. Ballots can be counted at the polling place—referred to as a precinct-count optical scan—or at a central location. If ballots are counted at the polling place, voters or election officials put the ballots into the tabulation equipment, which tallies the votes; these tallies can be captured in removable storage media that are transported to a central tally location, or they can be electronically transmitted from the polling place to the central tally location. If ballots are centrally counted, voters drop ballots into sealed boxes and election officials transfer the sealed boxes to the central location after the polls close, where election officials run the ballots through the tabulation equipment in the presence of observers. Software instructs the tabulation equipment how to assign each vote (i.e., to assign valid marks on the ballot to the proper candidate or issue). In addition to identifying the particular contests and candidates, the software can be configured to capture, for example, straight party voting and vote- for-no-more-than-N contests. Precinct-based optical scanners can also be programmed to detect overvotes (where the voter votes for two candidates for one office, for example, invalidating the vote) and undervotes (where the voter does not vote for all contests or issues on the ballot) and to take some action in response (rejecting the ballot, for instance). In addition, optical scan systems often use vote-tally software to tally the vote totals from one or more vote tabulation devices. If election officials program precinct-based optical scan systems to detect and reject overvotes and undervotes, voters can fix their mistakes before leaving the polling place. However, if voters are unwilling or unable to correct their ballots, a poll worker can manually override the program and accept the ballot, even though it has been overvoted or undervoted. If ballots are tabulated centrally, voters would not be able to correct any mistakes that may have been made. Direct Recording Electronic (DRE) Systems. First introduced in the 1970s, DREs capture votes electronically, without the use of paper ballots. According to Election Data Services, Inc., about 12 percent of voters used this type of technology in the 2000 elections and about 29 percent of voters used this technology in the 2004 elections. DREs come in two basic models: pushbutton or touchscreen. The pushbutton model is the older technology and is larger and heavier than the touchscreen model (see fig. 3). Pushbutton and touchscreen models also differ significantly in the way they present ballots to the voter. With the pushbutton model, all ballot information is presented on a single “full-face” ballot. For example, a ballot may have 50 buttons on a 3- by 3-foot ballot, with a candidate or issue next to each button. In contrast, touchscreen DREs display the ballot information on an electronic display screen. For both pushbutton and touchscreen models, the ballot information is programmed onto an electronic storage medium, which is then uploaded to the machine. Both models rely on ballot definition files to tell the voting machine software how to display ballot information on the screen, interpret a voter's touches on a button or screen, and record and tally those selections as votes. Local jurisdictions can program these files before each election or outsource their programming to a vendor. For touchscreens, ballot information can be displayed in color and can incorporate pictures of the candidates. Because the ballot space on a touchscreen is much smaller than on a pushbutton machine, voters who use touchscreens must page through the ballot information. Despite their differences, the two DRE models have some similarities, such as how the voter interacts with the voting equipment. For pushbutton models, voters press a button next to the candidate or issue, which then lights up to indicate the selection. Similarly, voters using touchscreens make their selections by touching the screen next to the candidate or issue, which is then highlighted. When voters have finished making their selections on a touchscreen or a pushbutton model, they cast their votes by pressing a final “vote” button or screen. Until they hit this final button or screen, voters can change their selections. Both models also allow voters to write in candidates. While most DREs allow voters to type write-ins on a keyboard, some pushbutton types require voters to write the name on paper tape that is part of the device. Further, although these systems do not use paper ballots, they retain permanent electronic images of all the ballots, which can be stored on various media, including internal hard disk drives, flash cards, or memory cartridges. According to vendors, these ballot images can be printed and used for auditing and recounts. Some of the newer DREs use smart cards as a security feature. Smart cards are plastic devices—about the size of a credit card—that use integrated circuit chips to store and process data, much like a computer. These cards are generally used as a means to open polls and to authorize voter access to ballots. For instance, smart cards for some systems store program data on the election and are used to help set up the equipment; during setup, election workers verify that the card is for the proper election. Other systems are programmed to automatically activate when the voter inserts a smart card; the card brings up the correct ballot onto the screen. In general, the interface with the voter is very similar to that of an automated teller machine.