There have been two Williams’s counties in the history of North Dakota. The first was created in 1873, and was located south of the Missouri River near where Dunn and Mercer counties are today.
The second Williams County was established by the 1891 state legislature and consists of the contemporary Williams and Divide counties. The name comes from Erastus Appelman Williams, an early politician from Bismarck who served in both the territorial and state legislatures. The county government was first organized on December 8, 1891; Williston has always been the county seat.