Louisiana is a city in Pike County, Missouri, United States. The population was 3,364 at the 2010 census. Louisiana is located in northeast Missouri, on the Mississippi River, south of Hannibal.

Pike County is a county on the eastern border of the U.S. state of Missouri, bounded by the Mississippi River. As of the 2020 census, the population was 17,587. Its county seat is Bowling Green. Its namesake was a city in middle Kentucky, a region from where many early migrants came. The county was organized December 14, 1818, and named for explorer Zebulon Pike. The folksong "Sweet Betsy from Pike" is generally thought to be associated with Pike County, Missouri.