The eastern lands were at first annexed to the Province of Venice; on 1851 the whole Po delta was detached from the Province of Venice and attached to the Province of Rovigo, thus giving the Polesine the extension it has nowadays.
Idapoolsed maad liideti algselt Veneetsia provintsiga, kuid aastal 1851 lahutati kogu Po jõe delta Veneetsia provintsist ja liideti Rovigo provintsiga, andes seeläbi Polesinele selle tänapäevase ulatuse.