While most of us enjoyed fireworks, baseball and barbecues over the Fourth of July weekend, a dozen or so enterprising volunteers in the city where the Declaration of Independence was signed may have signed on to their computers to keep the flame of liberty alive.

Recruited and organized by Philadelphia's most venerable good-government group, the Internet Archive and the Sunlight Foundation, the volunteers aim to record and analyze the media landscape in one key political market in the months leading up to Election Day.

The plan: to create a repository of all the political communications we can scoop up in the Philadelphia area and match them, to the best of our ability, with data on who is buying the ads and what we know about the political donors. Philadelphia voters will be bombarded with ads in a number of competitive races this fall. Besides the contest for Pennsylvania governor, there will be competitive races for three area House seats, in Pennsylvania's 6th and 8th Congressional Districts and in the 3rd Congressional District of New Jersey.

The Internet Archive and Sunlight will provide the technology and the data; volunteers will help us get it into shape for analysis and interpretation.

In an environment when too many Americans think there is nothing they can do to keep big money from overrunning their democracy, this collaboration offers a chance to help find out who the big political players are, what they're spending, what messages they're offering, and who's behind them. It lets citizens follow the money instead of being swamped by the ads that money buys.

For the past two years, the Sunlight Foundation has been focused creating an online archive of the contracts for political television commercials as a way to begin tracking spending in politics that otherwise is off the public radar. These days many of the biggest campaign spenders don't register with the Federal Election Commission, operating instead as nonprofit groups -- exempt from disclosing donors and much of their spending.

But there is one place where these dark money groups leave a paper trail: the local TV stations where they buy their ads. Sunlight, along with other transparency groups such as Free Press, advocated for online posting of those files in 2012, and when the Federal Communication Commission went along with the idea, we created Political Ad Sleuth to make them searchable and sortable. Now we're asking volunteers to help us enter information from the Philadelphia market into a database so we can identify who's behind the ads and how much they are spending.

The Internet Archive meanwhile, is collaborating with the University of Pennsylvania's Linguistics Data Consortium to add the region's television news broadcasts and political advertising to the Archives' television news research library. The archived video will be available 24 hours after it is broadcast. Because the Archive intends to make its video data searchable, and because the political ad contracts in Ad Sleuth include the date and time a commercial is to be aired, it will be possible to link an advertisement directly to the money -- and, we hope, the source of the money -- that paid for it.

Scholars such as the University of Delaware's Danilo Yanich are already interested in using the data, as are journalists from the Philadelphia Inquirer and Daily News. But the biggest beneficiaries will be voters, who now will be able to learn the agendas of the groups trying to influence their vote. Who exactly are "Philadelphians for a Better Philadelphia?" or "Broad Streeters for Improved Cheesesteaks?" (The sorts of feel-good but uninformative names these mystery meat political committees sport.) Are they your local PTA? Or your local toxic waste dump? Before you act on their recommendation to vote for (or against) a politician, you should know.

Thomas Jefferson, author of the great Declaration that gave birth to the United States 236 years ago, famously said that "eternal vigilance is the price of liberty." With our work in the city where the Declaration of Independence was signed, the Internet Archive and the Sunlight Foundation hope to continue that vigilance, 21st century style.

The Sunlight Foundation is a nonprofit, nonpartisan organization that uses the power of the Internet to catalyze greater government openness and transparency, and provides new tools and resources for media and citizens, alike. A list of Sunlight's funders can be found here.