Smithfield is located in Fulton county Illinois with a geographic area of 0.5 square miles. The total population in Smithfield is 181 with 53.0% male and 47.0% female. Children under age 5 represent 2.2% of the population, under age 18 equal 11.6% of the population and over age 65 is 32.6% of the population. The median household income is $43,750, per capita income is $26,699. There are a total of 100 housing units with 90.0% owner occupied. Education includes 44.0% of residents that are high school graduates and 11.0% with a bachelor's degree or higher. The average temperature in Smithfield in the summer is 74 degrees, and in the winter 27 degrees.