Newcomers from Germany as well as German Americans from St. Louis began arriving shortly before the war, with many more to come afterwards. They eventually made up a large part of the populations of Concordia, Emma, Wellington, Napoleon, Higginsville, Mayview, and Lexington. The German immigrants generally supported the Union during the war.
Peter Youree, who commissioned the first skyscraper in Shreveport, Louisiana, a 10-storey headquarters building for the Commercial National Bank, of which he was president, was born in Lafayette County in 1843 and grew up there. He settled in Shreveport after the Civil War and became a successful businessman and banker.
In November 2013, Leland Ray Kolkmeyer plead guilty, in federal court, of a fraud scheme in which he embezzled more than $1.5 million from Wellington-Napoleon Fire Protection District and Special Road District while being their former treasurer.
According to the 2000 U.S. Census, the county has a total area of 638.86 square miles (1,654.6 km2), of which 629.31 square miles (1,629.9 km2) (or 98.51%) is land and 9.55 square miles (24.7 km2) (or 1.49%) is water.
There were 12,569 households out of which 33.90% had children under the age of 18 living with them, 59.30% were married couples living together, 9.40% had a female householder with no husband present, and 27.60% were non-families. 24.00% of all households were made up of individuals and 11.20% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 3.01.
In the county the population was spread out with 26.20% under the age of 18, 7.60% from 18 to 24, 27.50% from 25 to 44, 23.30% from 45 to 64, and 15.40% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 95.90 males. For every 100 females age 18 and over, there were 92.00 males.
The median income for a household in the county was $38,235, and the median income for a family was $45,717. Males had a median income of $31,972 versus $22,684 for females. The per capita income for the county was $18,493. About 6.90% of families and 8.80% of the population were below the poverty line, including 10.90% of those under age 18 and 9.10% of those ages 65 or over.