Users Tinker With Google Maps to Provide Other Useful Data

Associated Press

Tracking sexual predators in Florida. Guiding travelers to the cheapest gas. Pinpointing $1,500 studio apartments for rent in Manhattan.

Geeks, tinkerers and innovators are crashing the Google party, having discovered how to tinker with the search engine’s mapping service to graphically illustrate vital information that might otherwise be ignored, overlooked or not perceived as clearly.

Yahoo and other sites also offer maps, but Google Inc.’s 4-month-old mapping service is more easily accessible and manipulated by outsiders, the tinkerers say.


As it turns out, Google charts each point on its maps by latitude and longitude -- that’s how the Mountain View, Calif.-based company’s website can produce driving directions to practically anywhere in the nation. Seasoned developers have figured out how to match these points with locations from outside databases that can contain vast amounts of information -- data as diverse as police blotters and real estate listings.

Thanks to Adrian Holovaty, who overlaid Chicago Police Department crime statistics on a Google map, house hunters in the Albany Park neighborhood can pinpoint all the sexual assaults in the district on a map. With each crime marked by a virtual pushpin, Chicagoans can quickly learn what dangerous train stations and alleys to avoid.

Holovaty hopes to make the maps more current by persuading Chicago police to provide the data directly, instead of forcing him to glean it from the department’s website. Police seem amenable -- he has a meeting with them next week. But community activist James Cappleman is already impressed with Holovaty’s -- no longer do citizens have to trust politicians crowing about safer streets.

“We’ve never been able to track trends before,” Cappleman said. “Now, when we tell police there is a problem, we’ll know what we’re talking about.”

Visitors to Floridasexual, which combines Google Maps with data on convicted sex offenders, can call up maps of their communities and click on the pushpins to see the name, last known address and mug shot of each offender.

Drivers searching for their area’s cheapest gas can go to, which blends Google Maps with data from’s database of prices at gas stations.


Home buyers can pinpoint the locations of houses in their price range at And renters can turn to Housingmaps .com, which melds the technologies of Craigslist and Google, to spot available housing in 29 cities including Los Angeles, San Francisco, New York and Chicago.

All these sites are operating without Google’s permission, clearly violating the company’s user agreement. But none charges any fees, and Google, which declined to comment through a spokesman, has made no effort to shut them down.

“Why would they?” asks Kenneth Tan, who works for a Chicago-based media research firm and is relying on Housingmaps .com to find a new place in New York. “This is fantastic publicity for the company.”

Before launched in March, Tan spent up to 30 minutes a day reading through Craigslist postings in his price range, trying to figure out whether any was located where he wants to live.

On, the listings he wants are represented on a single map, marked by either a red or yellow pushpin symbol. Yellow comes with apartment photographs; red has none. A click on a yellow pin sends Tan directly into the Craigslist posting on the street where he hopes to live.

“It takes two seconds to glance at the map to see if there is anything for me that day,” Tan said.


Computer animation engineer Paul Rademacher developed shortly after Google Maps launched in February, matching it with all the U.S. apartment listings on Craigslist. He says he was intrigued by Google’s technology and began tinkering with it after a long apartment search.

James Brown, founder of, charted the home addresses of every registered sex offender in Florida’s Megan’s Law database, then wrote a software program that automatically converts addresses to the correct latitude and longitude.

Holovaty requested data from Chicago police but never heard back, so he wrote a program that automatically retrieves crime location data each time the department’s website is updated.

Why go to this much trouble?

The sites’ creators said it was for the love of discovery and a chance to help their communities.

Brown came up with the idea for his site after watching television reports about a kidnapped girl with his dad, a former policeman in Ocala, Fla. Rademacher said he wanted to help others avoid painstaking and time-consuming searches for new apartments.

“I figured out a way to do it, and I didn’t see any reason why I shouldn’t share it with everybody,” said Rademacher, who lives in Santa Clara, Calif.