Which river was used as a major trade route for the midwestern United States?

The Mississippi River is the correct answer.

The Mississippi River is located in the midwestern area of the United States. This river runs from Minnesota to the Gulf of Mexico. As one of the largest rivers in the United States, the Mississippi River has been used as an important trade route for Native American tribes located around the area of the river, even before Europeans settled in America.

The Arkansas river was use as a major trade route for the Midwestern United states.