As a result of the Seat of Government Surrender Act 1909, a large part of the New South Wales County of Cowley was transferred to the Commonwealth to make up the western part of the Australian Capital Territory in 1909. The parishes of the County of Cowley that were completely or partly absorbed included Boboyan, Booroomba, Brayshaw, Congwarra, Cotter, Fergus, Gibraltar, Greenfield, Gudgenby, Milligan, Naas, Orroral, Punyibah, Tharwa, and Tidbinbilla. The northeastern part of the Australian Capital Territory was made up of parishes within the County of Murray. The dividing line between these two counties is the Murrumbidgee River. All parishes that transferred wholly within the borders of the Australian Capital Territory eventually ceased to exist as parishes.