International Drivers License
You will be able to find insurance through major US companies -- but one of the requirements is usually an "international drivers license." Make sure you get one of those before you arrive and bring it with you. An insurance agent is probably the best source for information about what types of coverage you need, but I'd ask several so you can compare the answers and weed out the ones that are simply trying to sell as much coverage as possible. Also, because of your young age, your costs will be higher. Here's the text of an earlier post on this same topic:
"While you may drive a vehicle in the USA with your [foreign] driver's license, it probably will not be possible for you to purchase insurance without a US (state) driver license, or an "international" driver license.
As foreign citizens, you won't be able to finance a car here as you won't have any credit "history," but it sounds like you intend to pay cash for the vehicle, so no problem there.
Then, you'll need to register the vehicle (you'll probably need a "residence" address in the state where you register the car -- and the rules will be different from state to state). Some states may be more restrictive on this than others. Have your friends here check out those requirements for you so you know what you have to do.
For insurance, contact an insurance broker and they can help you find a company to insure you (one such company is called "Progressive," they are a major US provider of insurance) -- but you'll need to get the International driver license before you arrive.
You might also contact your Consulate -- they may have more information about this subject, since for sure others have had the same questions.
Bob