Dortmund is, with a population of 601,402 (2017), the third largest city of Germany's most populous federal state of North Rhine-Westphalia after Cologne and Düsseldorf, and Germany's eighth largest city. It is the largest city of the Ruhr, Germany's largest urban area with some 5.1 million (2011) inhabitants, as well as the largest city of Westphalia. On the Emscher and Ruhr rivers, it lies in the Rhine-Ruhr Metropolitan Region and is considered the administrative, commercial and cultural centre of the eastern Ruhr. After Hamburg, Dortmund is the second largest and one of the southernmost cities in the Low German dialect area. Dortmund Airport is the city's international airport in the eastern borough of Wickede, but the main airport for the Ruhr is Düsseldorf Airport in Düsseldorf-Lohausen.