Is there a public geolocation system that I can query for names of local cities?

Question

I'm looking to attempt to simplify address entry into a system where the city textbox has autosuggest initially populated by the user's geolocation. In the past it has seemed that autosuggesting the city name is prohibitively costly without knowing the province/state/country first but it doesn't make sense to require the user to enter the address backwards as we don't think about address information this way. On the other hand, not autosuggesting the city name means we end up with all sorts of weird and wonderful entries for mis-spelled cities from around the world.

I was wondering if there's a service that I can query that would automatically respond with the most appropriate city names according to not only what the user enters in the textbox, but the location of that user based on the country and political boundary they fall within?

For instance, if I am in Canada [as I am] and I enter 'Mi' then I'd be presented with all cities within Canada starting with 'Mi' until it was determined that the information I was entering wasn't Canadian at which point, it would use the next most likely configured country based on our usage pattern - i.e. it would check the U.S. next, followed by Mexico and then other less likely destinations. I can write all this myself if I had the database but I don't know where I can find one and my suspicion is that it would be less scalable than querying a pre-existing service on the web.

Answer 1

Looks as though MaxMind offers a free database that you could download in CSV: http://www.maxmind.com/app/geolitecity

There's an online demo to test it a bit if you'd like, but no way to query it through a web service.

IPInfoDB also has their database available for download: http://ipinfodb.com/ip_database.php - they have an XML API, but it only supports looking up the city/country for a particular IP. You're trying to do something a little more wide than that, looking for every city in a particular country, with country selected based on IP. I wouldn't expect that there's a web service for that, it's a pretty specific requirement.

Edited to add: You could use the IPInfoDB API to look up the country though, and then generate the autocomplete suggestions from a local country/city database. That way all the IP-geolocation wouldn't need to be done locally. There are various places that you can get a list of cities in a particular country. For example, here's some comprehensive lists maintained by the National Geospatial-Intelligence Agency: http://earth-info.nga.mil/gns/html/cntry_files.html