However, the state supreme court overturned the legislature's act on May 24, 1901; in effect re-creating Dunn County.

On March 13, 1903, the legislature again voted to dissolve Dunn County, but again (during the 1905 session) the state supreme court voided the act.

In the process, Dunn gained a tract of previously unattached land from Stark County, enlarging its boundary.

The county was named for John Piatt Dunn,[3] who opened the first drugstore in North Dakota, and who was a civic and commercial leader during the early history of Bismarck.

The county terrain consists of semi-arid rolling hills, which are etched in the north and east by gullies and drainages to the river valleys.

[6] The terrain slopes to the east and north; its highest point is a hill at the southwestern corner, at 2,625 ft (800 m) ASL.

These hills help create a mini-ecosystem on the southern edge of the Little Missouri badlands, which has a greater abundance of aspen forests and wildlife than is typically found in southwestern North Dakota.

In terms of ancestry, 57.6% were German, 20.3% were Norwegian, 8.5% were Czech, 6.0% were Russian, 5.7% were Irish, 5.3% were English, and 1.8% were American.