Under Prussian rule, Siegen developed into the South Westphalian centre that it is today. On 1 March 1923, Siegen was set apart from the district bearing its name, and became a district-free town, while still keeping its function as seat of the district of which it was no longer part, and which was itself merged with Wittgenstein district under district reform in 1975. Siegen also lost its district-free status at this time, becoming part of the new Siegen-Wittgenstein district, the name that the district has borne since 1984.