By the 1960s over half of the votes in the United States were cast on lever machines. Another type of mechanical voting machine was the punch-card machine, developed in the 1950s and 1960s. Voters used a supplied device to punch holes opposite their preferred candidates' names on the ballot cards. After the polls closed, the results were tabulated by mechanical card counters. Optical scanning voting systems were developed in the 1970s.
Voters make marks on paper ballots to indicate their choice of candidates.
A scanning device then reads the marked entries to calculate the results. These systems allow the voter to directly record votes using a computerised ballot display provided via mechanical or electro-optical devices. Once the voter has made his or her ballot selections, the device processes the data with a computer program and records voting data and ballot images into internal memory devices, which are used to tabulate the results. Beginning in the 1990s the telephone was also used as a type of DRE voting system. Voters were able to record their votes directly into computer systems using the key pad on the telephone.