Winfield is a city in Lincoln County, Missouri, United States. Winfield was laid out in 1879, and named after Winfield Scott Killam, the original owner of the town site. A post office called Winfield has been in operation since 1880.
The median income for a household in the city was $36,167, and the median income for a family was $45,536. Males had a median income of $35,313 versus $21,071 for females. The per capita income for the city was $17,740. About 10.0% of families and 15.8% of the population were below the poverty line, including 19.0% of those under age 18 and 13.5% of those age 65 or over.