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.
City
Zip Codes
58102 58104 58103 58105 58106 58107 58108 58109 58121 58122 58124 58125 58126
58505 58504 58501 58503 58507
58202 58203 58201 58206 58208
58707 58703 58701 58702
58078
58801 58802 58803
58601 58602
58554
58401 58402 58405
58075 58076
58072
58854
58705 58704
58237
58504
58047
58523
58763
58204 58205
58545
58368
58012
58318
58421
58054
58784
58474
58257
58249
58316
58341
58045
58623
58540
58270
58577
58722
58785
58251
58356
58220
58852
58770
58324
58316
58278
58367
58059
58335
58790
58639
58730
58436
58027
58621