Each state has its own requirements for establishing residency for voting purposes.
You establish a voting residence address by living in a location with an intent to make the location your home.
Renting or buying property, establishing utilities accounts, registering your car, obtaining a driver's license, registering to vote - these are all actions that indicate an intent to make your home in a given location.
Each state has its own requirements for establishing residency for voting purposes. You may find this site useful: http://www.infoplease.com/ipa/A0781452.html
If you have additional questions, please contact your local election office. You can find contact information in the Election Official Directory on our website.
If you are a US citizen born overseas, please see related article: "As an American born overseas, can I vote?" for further information.