Thief River Falls, sometimes referred to as Thief River or edited as TRF, is a city in Pennington County in the northwest allowance of the U.S. state of Minnesota. The population was 8,749 at the 2020 census. Thief River Falls is the county seat for Pennington County.

Thief River Falls takes its name from a geographic feature, the falls of the Red Lake River at its confluence similar to the Thief River. The publicize of the river is a in limbo translation of the Ojibwe phrase Gimood-akiwi ziibi, literally, the “Stolen-land river” or “Thieving-land river”, which originated later than a band of Dakota Indians occupied a mysterious encampment along the river, hence “stealing” the land, before innate discovered and routed by the against Ojibwe. In the Treaty of Old Crossing of 1863, the Moose Dung’s Indian Reservation was established on the west bank of the Thief River, at its confluence once Red Lake River. This Indian Reservation was dissolved in 1904 and their population incorporated as share of the Red Lake Band of Chippewa.

Thief River Falls marked the limit of navigation upon the Red Lake River. The eponymous town site was received in 1887 and higher incorporated as a city in 1896. Thief River Falls first developed as a lumber-milling town. It is located in a major agriculture Place because of the wealthy soil left by ancient Glacial Lake Agassiz. The Great Northern and the Soo Line railroads brought prosperity when Thief River Falls became a middle for shipping wheat.

According to the United States Census Bureau, the city has a total area of 5.21 square miles (13.49 km), of which 5.02 square miles (13.00 km²) is home and 0.19 square miles (0.49 km) is water.