Louisiana is a state located in the southern region of the United States of America. Louisiana is the 31st most extensive and the 25th most populous of the 50 United States. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties. The largest parish by population is East Baton Rouge Parish, and the largest by land area is Cameron Parish.
Much of the state was formed from sediment washed down the Mississippi River, leaving enormous deltas and vast areas of coastal marsh and swamp. These contain a rich southern biota; typical examples include birds such as ibis and egrets. There are also many species of tree frogs, and fish such as sturgeon and paddlefish. In more elevated areas, fire is a natural process in the landscape, and has produced extensive areas of longleaf pine forest and wet savannas. These support an exceptionally large number of plant species including many species of orchids and carnivorus plants.