Before Iowa achieved statehood in 1846, one abbreviation for Indiana was "Ia.," and many census enumerators continued to use "Ia." as the abbreviation for Indiana well after 1846, simply not abbreviating, Iowa, at all.  In the 1850 census, indexers at Ancestry.com have mis-interpreted birthplace, "Ia.," as meaning, "Iowa," with the absurd result, for example, that over 100,000 people in Indiana in 1850 are shown as born in Iowa.  So, when you find the abbreviation, "Ia.," as an individual's birthplace in the census, use your head in interpreting whether it meant Indiana or Iowa.