Iowa was opened, organized, and settled by a generation of native migrants from other states. According to the first federal census of Iowa in 1850, 31% of the total population of 192,214 came from nearby midwestern states (Illinois, Wisconsin, Indiana, Michigan, and Ohio), 14% from the five southern border states, and 13% from the Middle Atlantic states.

Another 10% of the state's 1850 population consisted of immigrants from northern Europe. The largest group were Germans who had fled military conscription; the next largest group had sought to escape the hardships of potato famine in Ireland or of agricultural and technological displacement in Scotland, England, and Wales. They were joined in the 1850s by Dutch immigrants seeking religious liberty, and in the 1860s and 1870s by Norwegians and Swedes. During and immediately after the Civil War, some former slaves fled the South for Iowa, and more blacks settled in Iowa cities after 1900.

But many of the migrants who came to Iowa did not stay long. Some Iowans left to join the gold rush, and others settled lands in the West. Migration out of the state has continued to this day as retired Iowans seeking warmer climates have moved to California and other southwestern states; from 1970 through 1990, Iowa's net loss through migration amounted to over 266,000.

An important migratory trend within the state has been from the farm to the city. Although Iowa has remained a major agricultural state, the urban population surpassed the rural population by 1960 and increased to over 60.6% of the total population by 1990. Between 1990 and 1998, Iowa had a net loss of 13,000 in domestic migration and a net gain of 19,000 in international migration. In 1998, 1,655 foreign immigrants arrived in the state. Between 1990 and 1998, Iowa's overall population increased by 3.1%. In the period 1995–2000, 214,841 people moved into the state and 247,853 moved out, for a net loss of 33,012, about 28,695 of whom moved to Illinois.