Jefferson County was formed in 1856 and was named for Thomas Jefferson, third president of the United States. Area Page: Eastern South Nebraska AreaCounty Seat: Fairbury NebraskaLicense Platte Prefix: 33Census 2010: 7,547Cities Towns in the County: Fairbury NebraskaCounty Map with Cities: Jefferson County MapWebsite - County: Jefferson County Nebraska Official WebsiteWebsite - County Fair: Jefferson County Nebraska County Fair