No. There s no such thing as unclaimed/unowned territory in the U.S. any more. Go to the county tax assessors office and you ll be able to find out who owns what piece of property.
maybe in Alaska, Montana or Maine, but contact the government to see about that. There may be some land being auctioned off or sold cheap for unpaid taxes. Detroit has a lot of abandoned homes that you could probably get for almost nothing in but it s not a safe city.