Which American river flows predominantly to the north?

The Red River of the North is the correct choice because it is one of the few major rivers in the United States that primarily flows northward. Originating in the state of North Dakota, it winds its way through Minnesota before ultimately emptying into Lake Winnipeg in Canada. The characteristic northward flow is a unique feature of this river, distinguishing it from many other rivers in the country that typically flow toward the south or east.

In contrast, the other rivers mentioned have different flow patterns. The Delaware River flows primarily southeast, the Ohio River flows generally west to east, and the Hudson River flows primarily southward from its source in the Adirondack Mountains to its mouth at the New York Harbor. This makes the Red River of the North the only one among the listed options that flows predominantly to the north.