Fairfield is a city in, and the county seat of, Jefferson County, Iowa, United States. It has a population totaling 9,464 people according to the 2010 census. It is a Midwestern city surrounded by rolling farmlands filled with corn, soybean, cattle, and hogs with a median family income of $46,138. The city became the county seat in 1839 with 110 residents and grew to 650 by 1847. Its library was established in 1853, and it held its first fair in 1854. Early architecture includes work by George Franklin Barber and Barry Byrne, who trained under Frank Lloyd Wright.The city has an “abundance of start-up companies” and has been called "one of the state's economic superstars." It has received The Grassroots Rural Entrepreneurship Award, has been nicknamed “silicorn valley,” and was featured in a 2012 episode of the TV show, Oprah's Next Chapter.