First and foremost, use paper ballots. Before anything else. The paper ballots are the System of Record. If ever in doubt about downstream results, paper ballots can be hand-counted. (Additionally, use paper voter rolls. Mark registered voters when they vote, and track any same-day registrations on paper. The exact number of ballots cast can be extracted from the voter rolls.)<p>Second, <i>never</i> allow paper ballots to be handled by just one person, or by only members of one party - whether blank or used. Require that members of at least two political parties be present any time the ballots are physically touched.<p>Third, if using machines to read the ballots (ScanTron, etc), conduct spot counts of random machines, to make sure the machine results match the paper ballots. Conduct spot counts of entire polling stations randomly to make sure result totals match voter roll totals. Although this isn't 100% certain, it doesn't take a lot of spot checks to detect any sort of large-scale fraud effort.<p>Do these things, and it's exceedingly difficult to do statistically meaningful vote fraud, because we have a high degree of trust in the paper ballots and their surrounding process. From there, you can use automatic ballot reading and tallying to get fast results - the vote counting/tallying automation is derived data, not the System of Record.