Smithfield is a village in Fulton County, Illinois, United States. The population was 230 at the 2010 census. The village is named in honor of Dr. Joseph N. Smith.Smithfield is located in western Fulton County at 40°28′23″N 90°17′34″W / 40.47306°N 90.29278°W / 40.47306; -90.29278. Illinois Route 95 forms the northern edge of the village; the highway leads east 6 miles to Cuba and west 5.5 miles to Marietta. Lewistown, the county seat, is 12 miles to the southeast via IL 95 and IL 97.According to the 2010 census, Smithfield has a total area of 0.46 square miles, all land.Smithfield is served by the Keokuk Junction Railway, a subsidiary of Pioneer Railcorp. BNSF once used the tracks through Smithfeild.As of the census of 2000, there were 214 people, 95 households, and 66 families residing in the village. The population density was 450.0 people per square mile. There were 103 housing units at an average density of 216.6 per square mile. The racial makeup of the village was 99.