The
Aller is a long river in the states of
Saxony-Anhalt and
Lower Saxony in Germany. It is a right-hand, and hence eastern, tributary of the
River Weser and is also its largest tributary. Its last form the Lower Aller federal waterway (
Bundeswasserstraße). The Aller was extensively straightened, widened and, in places, dyked, during the 1960s to provide flood control of the river. In a long section near
Gifhorn, the river
meanders in its natural river bed.