Slope County, North Dakota: History
The vote to create Slope County, by partitioning the lower portion of Billings, was held on November 3, 1914. This was the final (as of 2019) alteration to that once-large Dakota county, as Bowman had been partitioned off in 1883, and Golden Valley was split off in 1910. The unorganized Slope County was not attached to another county for administrative or judicial purposes during the interregnum; on January 14, 1915, the county organization was effected. The name refers to the Missouri Slope, a geographical feature that is also a popular designation for western North Dakota, particularly the area west of the Missouri River.