Over the past few years, cities have put a fair amount of energy into open data initiatives, and, through app contests and “hackathon” events, they’ve encouraged citizens and businesses to create new software applications based on the information. But while cities have been good at promoting open data innovation, they haven’t been as good at coordinating their activities.

Civic hackathon events in multiple cities often tackle the same problems and produce similar -- but incompatible -- applications. “We’re all trying to create the same applications over and over again,” says San Francisco CIO Jon Walton. “At some point, that doesn’t really make sense.”

That’s about to change.

Walton is part of an informal group of CIOs from seven of the nation’s largest cities. Known as the G7 (or group of seven), they’ve held regular conversations since 2009 to commiserate and trade ideas. Now they’re launching their first formal project: A website that will house standardized data from member cities -- Boston, Chicago, Los Angeles, New York City, Philadelphia, San Francisco and Seattle -- making it easier for them to share applications.

The unified database means applications developed for one G7 city should work for all. The group also intends to hold multi-city hackathons that will target common problems and produce shared results.

Open data already has proven a powerful idea for city governments. Municipalities from New York to San Diego have opened government data streams to the local software development communities, reaping scores of new software applications. In San Francisco, developers have used city and county data to create everything from SFpark, an iPhone app that shows the location of open parking spaces, to Mom Maps, which helps parents find kid-friendly parks and restaurants.

“One of the things that surprised some of us was the number of applications that people rush to build once you make this data public,” says Walton. “That’s a real boon to the city because I don’t have to spend taxpayer dollars to create them.”

Building those applications on standard data sets and coordinating multi-city development events will multiply the value of open data initiatives. For citizens, it’ll mean more applications as cities leverage one another’s efforts. It also will mean more convenience for app users. The same parking app that residents use in San Francisco, for instance, will work when they’re on vacation in Seattle or on a business trip to Chicago.

For political leaders in the G7 cities, the new approach also makes it easier to gauge performance against their peers. “When you work for a big-city mayor, one question that comes up a lot is, ‘How do we compare?’ How does our crime compare to New York? How does our permitting process compare to Chicago?” Walton says. “We’ll have a common set of data to do that comparative analysis.”

And the idea may not be confined to the original seven cities for long. The group has ties to the Obama administration’s technology team, which could produce cooperation between the G7’s new data initiative and the federal government’s data.gov portal. Chris Vein, Obama’s deputy chief technology officer, is the former San Francisco CIO and still participates in G7 discussions. Speaking at a Washington, D.C., technology event in March, Vein said the feds intend to broaden data.gov to include city data.

“We’re really trying to take this to the next level,” says Walton. It’s too early to say how the idea will play out, but it’s certainly worth keeping an eye on.