Ungava's southern continental boundaries initially ranged as far south as Lake Timiskaming, well below James Bay on the modern Ontario/Quebec border.

All told, the act transferred approximately 250,000 square kilometres (97,000 sq mi) of Ungava to Quebec, the majority of which now lies in the modern-day Jamésie region of the province.

After the transfer was complete, the mainland area of the District of Ungava reached no further south than the mouth of the Eastmain River—about halfway down James Bay, as shown on the accompanying map.

The Ungava district was largely inhabited by the aboriginal Cree, Innu (called "Montagnais" by French people), Naskapi, and Inuit.

[3] In 1927, the long-standing dispute over the location of the boundary between Labrador and the former District of Ungava (by then part of Quebec) was taken to the arbitration of the British Judicial Committee of the Privy Council, which ruled in favour of Newfoundland.