Residency and residence are two completely different concepts. Residency is a state requirement for voting and paying income tax. A residence, by contrast refers to where you live. Using the Postal Service to deliver important documents to your residence helps establish your home as a residence.
You can own as many homes as you want to, and treat them as your residences. Be aware of the difference between "residence" and "residency." Residency is a state requirement for voting and paying income tax. Usually, the state requires that you live a certain number of months within a state to be a resident of that state. You can own a residence in that state while having official residency status in another state. You can establish each residence with the United States Postal Service.
Send a piece of mail to your second home. According to the United States Postal Service publication 508, mail is delivered as addressed, not according to the name on the mail. You can receive mail at any address you wish. The Postal Service is not a clearing house for the legality of receiving mail at an address. In other words, you don't need permission from the post office to receive mail at your second address.
Maintain residency at your original home. A state can argue that if you spend most of your time at one residence, you have in fact established residency in that state and owe income taxes in that state. Make sure you have the Postal Service deliver non-state items such as federal tax notices, legal papers from out of state and magazines from national publishers to the residence you want to be recognized as your official residence. This will help you establish that the other residence is a second home.
Use two mail forwarding services. Hire someone to pick up your mail at each home and mail it to the home you are staying in. Do not ask the Postal Service to do this. Doing so may delay delivery and cause confusion. Hire a neighbor or a commercial mail-forwarding service to take care of the matter.
Have your mail held. If you don't want to go to the trouble of having mail forwarded, you can ask the Postal Service hold your mail while you are at your other residence. This method will not notify the local post office that you have moved, it will only tell them you are going out of town.
Each local post office will treat your local residence as an official place you receive mail, so don't worry about your status with the national U.S. Postal Service.
It is illegal to establish official state residency in two states at the same time. The reason for this is that states want to avoid voting fraud and want to know who owes state income tax. State colleges also offer lower tuition for in-state students, so they are interested in the location of your primary residence.