Scientific American: Votes by Mail Are Less Likely to Be Counted [View all]

Not really true in states that are all vote by mail, though.

http://readersupportednews.org/opinion2/277-75/14529-votes-by-mail-are-less-likely-to-be-counted

he biggest challenge to voting accuracy in the U.S. isn't hanging chads or hacked voting machines - it's the mail. A new report by the Voting Technology Project (VTP) - a joint venture between the California Institute of Technology and the Massachusetts Institute of Technology -finds that even though absentee ballots account for about only a quarter of all ballots cast during an election, the number of uncounted absentee and election-day ballots may be roughly the same.

The researchers estimate that up to 3.9 million absentee ballots were requested but not received by voters in the 2008 presidential election. Another 2.9 million ballots sent to voters requesting them were not returned for counting. And 800,000 returned absentee ballots were rejected for one reason or another. In all, 21 percent of requested absentee ballots were never counted in 2008 - 35.5 million requests for absentee ballots led to 27.9 million mail-in ballots being counted.

The number of unaccounted for mail-in votes is comparable to the number that fall through the cracks at in-precinct voting locations, a problem likely to grow as demand for more convenient methods of voting increases, according to the report. Votes cast by absentee and early voting have more than doubled in the past 12 years, leading the report's authors to warn that these voter-friendly initiatives could sabotage the accuracy of the overall election process.