What is "i-house"

The I-house is a vernacular house type, popular in the United States from the colonial period onward. The I-house was so named in the 1930s by Fred Kniffen, a cultural geographer at Louisiana State University who was a specialist in folk architecture. He identified and analyzed the type in his 1936 study of Louisiana house types. He chose the name "I-house" because of its common occurrence in the rural farm areas of Indiana, Illinois and Iowa, all states beginning in the letter "I". He did not use the term to imply that this house type originated in, or was restricted to, those three states.