There is no definitive answer to this question as there is no official body that keeps track of such things. However, it is generally agreed that the King Ranch in Texas is one of the largest ranches in the world. The ranch covers an area of around 825,000 acres (3,340 km2), making it larger than the state of Rhode Island. It has its own airport and its own police force. The ranch also has its own brand of beef, which is sold in supermarkets across the United States.