Which type of onion can only be legally grown in the state of Georgia?

According to the Vidalia Onion Act of 1986, Vidalia onions can only be grown in a designated region of the U.S. state of Georgia. Federal regulations protect the name "Vidalia," much like certain wines or cheeses are protected by their place of origin. To be labeled a Vidalia onion, the onion must be grown within a specific 20-county production area in southeastern Georgia. Their famously sweet, mild flavor is attributed to the region's low-sulfur soil and favorable growing conditions, making them highly sought after by consumers nationwide.