One side effect of Barack Obama’s Webcentric presidential campaign is that it helped turn the Democratic National Committee’s voter database–information on the political leanings and interests of millions of U.S. citizens–into a far more potent political weapon. In the final two months before Election Day, 223 million new pieces of data on voters accrued to the database, and the DNC now holds 10 times as much data on U.S. voters as at the end of the 2004 campaign, according to Voter Activation Network (VAN), a company based in Somerville, MA, that builds front-end software for the database.

Such information could prove vital for future elections in that it shows where to allocate resources most effectively–particularly when it comes to voters who are wavering between parties–and what kinds of messages will appeal to specific voters. While some of 223 million pieces of data added in the final stretch of the campaign are not particularly useful (it includes canvassers’ or callers’ notations that a voter “refused to talk” or “wasn’t home”), overall, it’s a gold mine, says Mark Sullivan, cofounder of VAN.

“The data collection in 2008 was a quantum leap from where we were in 2004,” Sullivan says. “It also means that we start the 2010 cycle with vastly more knowledge about who voters are, and how we can best communicate with them, rather than feeling like we have to start all over again.” This information could perhaps even help Obama govern if the DNC decides to ask average Americans to contact members of Congress about specific policy efforts related to, say, energy, health care, or the Iraq War.

The VAN database–Sullivan would not describe its exact size, but there are about 170 million registered voters in the United States–can be used by all Democratic candidates in national or state elections. In the case of primary campaigns, new data collected by a Democratic combatant is kept by the candidate and added to the national database after a winner emerges.

While most campaigns add something to the database, the biggest contributor this year was, of course, the Obama campaign. For example, tens of thousands of times, volunteers logged in to Obama’s social-networking site, my.barackobama.com (MyBO), and downloaded small batches of voter names and phone numbers, dialed them up, and followed various scripts. The aim was to learn their political and issue leanings, encourage people to vote for Obama and to ask supporters to make sure they go to the polls. These responses were recorded by the volunteers using a Web interface, adding to the database instantly.

In the final four days of the campaign alone, four million such calls were made through MyBO, says Jascha Franklin-Hodge, cofounder and CTO of Blue State Digital, which built MyBO as well as the interface to the VAN voter list. “This was just using our tools in that short window of time–never mind what the actual field organization was doing on the ground,” he says. MyBO was hardly the only source: the DNC, local campaign offices, traditional phone banks, and canvassers also added data in various ways.

Beyond the data gathered on voters, the Democrats and Obama also have access to a network of willing volunteers who can be used to recontact voters. “They’ve got a whole volunteer structure that gathered all this information that can be put to used in the 2010 midterms, and can hopefully be available for a reelection [of Obama],” Franklin-Hodge says. “There is a tremendous amount of data mining and analysis that goes on within the party and political organization that allows a better understanding of how people vote and how they make decisions.”

This approach–“microtargeting” voters based on their feelings toward specific issues–was once the domain of the Republican National Committee. But even leading Republican figures now acknowledge that the days of GOP voter-data dominance have ended. “For decades, the RNC has had a significant advantage in their voter file, and in their ability to identify and turn out voters,” says Mike Connell, founder of New Media Communications, an Ohio-based Republican new-media firm. “With the Obama campaign and the efforts over the last couple of years, [the Democrats] have made significant strides and have caught up.”

A key reason for the DNC’s data advance was a decision by DNC chairman Howard Dean to improve data sharing among Democratic organizations at the state level. “Four years ago, Howard Dean ‘got it,’” Connell says. “Not a lot of people give him credit, but he made a transformation.”

Since then, the DNC and VAN have steadily improved the database interfaces. This year, the newest tool in the arsenal was a Google Maps application developed by VAN that makes it far easier to chop up lists of voters in specific precincts for canvassers to personally visit. In the new application, called “turf-cutter,” voters’ homes are displayed as icons on a map. A few clicks of a mouse allow organizers to draw boundaries around clusters of voters’ homes and print out the resulting list for volunteers.

In the past two months, Sullivan says, activists from all Democratic campaigns have used this application 948,000 times, saving thousands of hours of man power, compared to manually figuring out how best to chop up a given district and dispatch volunteers in the most efficient manner. “Probably, on average, for each precinct, they would work with maps and highlighters,” says Sullivan. “I hear all the time, ‘That was a 45-minute job,’ and now they go in here and it takes a minute or two. It was the biggest bottleneck.”