Huntsville is a city located in the northern part of Alabama, in the Appalachian region of the USA. The city is located in Madison county and extends to its western neighbor, Limestone county. The city was founded in 1805 and became a municipality in 1811. The population of the city, which has a surface area of 554 km², is 180,105 as of 2010. It is the 4th largest city in Alabama in terms of population. The population of the Huntsville Metropolitan area was 417,593 in 2010. In terms of population density, it is the second busiest Metropolitan area of Alabama. This number reached 462,693 in 2018.