geocoding - What's the easiest way to do a one-time mass geocode? (580,000 US addresses)

I am working on a civics related project and I need to be able to display all the properties in the City of Philadelphia on a map, so I'll need to get the latitude & longitude for all 580,000 properties. (Only once)

Most APIs like Google/Yahoo have limits of 5,000 per day, and even BatchGeo has a similar limit.

Is there a way I can do a one-time geocoding of all these addresses?

Answer

You could try the Street Address to Coordinates tool from the Data Science Toolkit.

This API takes either a single string representing a postal address, or a JSON-encoded  
array of addresses, and returns a JSON object with a key for every address. The value 
for each key is either null if no information was found for the address, or an object 
containing location information, including country, region, city and latitude/longitude 
coordinates. Here's an example:

Not sure what the API limits are for Pete Warden's hosted copy but you could run the toolkit yourself and do your processing offline as @Devdatta suggests. There is a downloadable virtual machine that is contains all the tools in the website. Good luck :)