You should buy insurance in the state that your car is registered. You should register your car in the state you claim as your primary residence. Typically, people who have multiple residences claim one as their primary residence. This would be the address you use on your tax return, where you are registered to vote and where you maintain a valid drivers license. You should inform your insurance company that your vehicle will be kept at a different location at certain times of the year. They will let you know if there is anything special you need to do.You can comparison shop your policy here by getting a car insurance quote.