Louisiana () is a state in the Southern United States of America. It had a population of about 4,533,372 people in 2010. The state has a total area of about . Louisiana is the 25th largest state by population and the 31st largest state by area. Louisiana is also known by its nickname, "The Pelican State". The land that would become Louisiana was bought in the Louisiana Purchase in 1803. Louisiana became a state on April 30, 1812. It was the 18th state to become part of the United States. The people who live in the state are known as "Louisianans". The state's capital is Baton Rouge, and its largest city is New Orleans.