General Info
O’Brien County was established in 1851, organized in 1860 and named in honor of William Smith O’Brien, a prominent Irish politician. The first settlers to the area were Hannibal and Hannah Waterman and their daughter Emily who arrived to the area in 1856. Primghar was established to be the county seat which was challenged by residents of Sanborn and Sheldon, to no avail. Agriculture dominated early industry as residents farmed corn, oats, hay and raised cattle. Railroad development allowed for growth and by 1900 the population of O’Brien County had reached 16,985. Today O’Brien County is home to approximately 14,398 residents.