At an extra session of the Sixth Legislative Assembly of Michigan held in September, 1834, the Iowa District was divided into two counties by running a line due west from the lower end of Rock Island in the Mississippi River.

When Michigan became a state in 1836 the area became the Iowa District of western Wisconsin Territory—the region west of the Mississippi River.

The original boundaries of the territory, as established in 1838, included Minnesota and parts of the Dakotas, covering about 194,000 square miles (500,000 km2) of land.

When Iowa became a state on December 28, 1846, no provision was made for official organization of the remainder of the territory.

The situation was resolved when Minnesota Territory was organized on March 3, 1849, the day before the close of congress.