Nevadans register before voting in February's GOP presidential caucuses: Some 2.8 million Americans are registered in more than one state, and nearly 69,000 are registered in three states.

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he nation's voter-registration system is a wreck, according to a new report from the Pew Center on the States. Millions of invalid registrations remain on the books, including an "army of (potential) zombie voters" who remained registered long after they died. "Voter registration is the gateway to participating in our democracy," but the country's "antiquated, paper-based systems are plagued with errors and inefficiencies," says Pew's David Becker. "These problems waste taxpayer dollars, undermine voter confidence, and fuel partisan disputes over the integrity of our elections." Here, a look at the problem, by the numbers:

1.8 million
Deceased Americans whose voter registration remains active

2.75 million
People registered in more than one state

68,725
Voters registered in three states

1,807
Voters registered in more than three states

51 million
Americans who are eligible to vote, but are not registered

12 million
People registered under addresses that are old or have errors severe enough that mailings are unlikely to reach them

24 million
Voter registrations that are inaccurate or no longer valid — nearly 13 percent of the names currently on voter rolls nationwide

76
Percentage of eligible adults who are registered to vote in the U.S.

93
Percentage of eligible adults who are registered to vote in Canada

$4.13
Amount Oregon spent per voter to process registrations in 2008. On average, local election offices spent a third of their budgets to register voters, according to a 2001 study.

$0.35
Amount Canada spends to register each voter

Sources: Gawker, Pew Center on the States, Politico, The Hill