Specialized mapping software helped New York plot the addresses of people who had called to complain about having lost their heat during a recent cold snap. That helped determine precisely where the city should set up "heating centers" for New Yorkers to huddle in.
In fact, officials can make a few mouse clicks to see any number of trends swirling in the city of 8 million people: which neighborhoods are low on fire trucks, where the West Nile virus has appeared, or which streets were recently paved and should be off limits to digging.
Other cities too are increasingly using the technology to infuse efficiency and clarity into what would otherwise be simple civic drudgery.
The system, known as the Citywide Geographic Information Systems (GIS) Utility, combines aerial photography, census figures, crime statistics and other information submitted by city agencies and local utilities. Any or all of it can be overlaid on an interactive map that is so detailed it shows curb lines, trees, wires, traffic rules and vehicle height restrictions.
Cities and insurance companies have long produced minutely detailed maps of their realms. And in recent decades, individual agencies in many cities fired up mapping software to track their specific regulatory matters.
But until recently, city agencies and contractors have shared their information in any number of time-consuming ways, including just calling each other by phone.
Newer mapping systems, in contrast, use improvements in computer processing power to blend many different kinds of information from disparate agencies, vastly aiding urban planning.
In New York, for example, fire engine dispatchers generally heard about street closures in an ad hoc fashion - from firefighters who noticed roadblocks while on a grocery run or even while rushing to blazes. Now dispatchers can see street closures directly, by checking what transportation officials have added to the map database on their end.
GIS also has become a powerful homeland security tool.
New York's system, which has cost about $20 million to develop over the past decade, helped coordinate emergency responders on Sept. 11, 2001. And in the aftermath, the underlying map was combined with thermal data detected by low-flying planes to show where fires and dangerously hot steam lurked in the World Trade Center rubble.
Now, the GIS system is aiding security plans for this summer's Republican National Convention at Madison Square Garden.
Previously, such plans relied heavily on "paper maps that showed no more than a thin line representing a street," said Lawrence Knafo, deputy commissioner of the city's information-technology department.
While that helped determine which streets should be closed, or where to position police officers, the new system lets authorities do much more.
For example, GIS can measure streets and sidewalks to determine how many people will fit in a given space. Or building floor plans can be overlaid on the map, giving emergency agencies a wider perspective on how to plan for problems - and react to them if necessary.
"By assessing the location of something and then combining it with what's around it, you're able to make a decision you were never able to make before," said Erich Seamon, GIS manager for San Francisco, where City Hall uses mapping software to monitor resources and police tap it to track crimes by location.
In fact, GIS is so good at changing how things get done that some resistance is inevitable.
In a test on Staten Island, New York City officials used the system's knowledge of building sizes at each address to estimate the amount of garbage that certain streets ought to produce. The data helped plot the most efficient routes for trash pickup.
But officials in the technology department said they feared that expanding the mapping function to garbage pickup elsewhere in the city could rankle the sanitation workers' union.
Harry Nespoli, president of the union, said he was unaware of the GIS test, but expressed doubt that trash service could be improved by software.
"We are not computers, you know. We are human beings," he said. "Does a computer get lunch time? Does a computer sprain his ankle? Does a computer die like one of my members did the other day? We have very, very efficient managers on this job. They came up through the ranks. They know the best way to pick up the garbage."
Overall, however, not much about these systems is controversial. Their most sensitive data are walled off from the public on secure servers.
However, some morsels are plugged into public Web sites in New York and San Francisco, for example, that combine aerial images, zoning records and information about local schools, government representatives or cultural attractions.
New Zealand uses spatial software to make sure tectonic shifts are reflected in property records. In California's vineyard-rich Sonoma County, agricultural commissioners rely on GIS to decide whether to grant pesticide-spraying permits, because they can check within minutes what schools, homes and medical facilities lie near the fields in question.
"It's still an emerging technology, but it's come a long way in the last couple of years," said Paul Buzanski, Sonoma County's GIS manager. "It's almost endless what we can do with it."
By Brian Bergstein