The Middle Weser Region (German: Mittelweserregion) includes, in its fullest sense, the land along the Middle Weser between Minden and Bremen. It lies within the federal states of North Rhine-Westphalia, Lower Saxony and Bremen. However, the term is often used just to refer to the Lower Saxon part, because of the different political development of the three states and the cooperative associations formed in Lower Saxony some years ago (see below). The Lower Saxon part of the Middle Weser Region forms the geographical heart of this state. In the centre of the Middle Weser Region are the towns of Minden, Nienburg/Weser and Verden (Aller). In the extreme north, the city of Bremen, which is not part of Lower Saxony, has a very important influence on that area of Lower Saxony surrounding it.