Sheridan County, North Dakota: History
The Dakota Territory legislature created the county on January 4, 1873, naming it for Civil War General Philip Henry Sheridan. The county organization was not completed at that time, but the new county was not attached to another county for administrative or judicial purposes. In 1883 and again in 1887, the county boundaries were reduced, and on November 8, 1892, the county was dissolved, its remaining territory assigned to McLean. This lasted until the November 3, 1908 election, when McLean County voters chose to partition off the eastern portion of that unit into a new county, although the new boundaries were somewhat different from the former Sheridan. The new county government was effected on December 24 of that year.
Sheridan has been severely affected by out-migration; its population collapsed from 7,373 in 1930 to 1,321 by 2010. Its population decline of 38.4% from 1990 to 2016 was the highest among all North Dakota counties.