Mardi Gras is NOT just in New Orleans, but that is the city with the biggest celebration. I think Biloxi, MS, has an MG celebration, and let's not forget Carnival, which is a celebration for the same thing (the beginning of Lent, and Carnival translates to "farewell to the flesh", and people used to give up meat for lent), just a different name. Brazil and several cities in Europe celebrate Carnival.