North Dakota Trust Lands Completion Act This bill authorizes the Department of the Interior to exchange, at the election of North Dakota, certain federal land for certain state land of substantially equal value. Specifically, if North Dakota elects to relinquish a parcel of state land located wholly or partially within the boundaries of any Indian reservation or the Little Missouri National Grassland in North Dakota, the bill authorizes North Dakota to select one or more parcels of federal land of substantially equivalent value within that state. No later than 60 days after Interior approves North Dakota's selection of federal land, Interior shall initiate the actions necessary to convey the federal land to the state. As consideration for the conveyance of the federal land, North Dakota shall concurrently relinquish and convey the state land to Interior or, for a parcel that is located wholly or partially within the boundaries of the grassland, to the Department of Agriculture. Land conveyed to Interior that is within the boundaries of a reservation becomes part of the reservation on request of the tribe.