Brown County is a county located in the U.S. state of Illinois. As of the 2000 census, the population is 6,950. Its county seat is Mount Sterling, Illinois. It was formed from Schuyler County on Feb 1, 1839, it was named after Jacob Brown [1775-1828] who defeated the British at the Battle of Sackett's Harbor in 1813. He was a Brigadier General of NY volunteers during the early years of the War of 1812. By 1815, he was Commander-in-chief of the Army. He received a gold medal for his action at Chippewa, Erie, and Niagra. The County is part of the Military Tract, The Military Tract is land granted to veterans of the War of 1812.

Mount Sterling is the county-seat of Brown County, midway between Quincy and Jacksonville, on the Wabash Railway. As of the census of 2000, there were 6,950 people, 2,108 households, and 1,380 families residing in the county. The population density was 9/km? (23/mi?). There were 2,456 housing units at an average density of 3/km? (8/mi?). The racial makeup of the county was 80% White, 18% Black or African American, 1% Native American, and 1% from other races.

There were 2,108 households out of which 29% had children under the age of 18 living with them, 55% were married couples living together, 7% had a female householder with no husband present, and 38% were non-families. 31% of all households were made up of individuals and 14% had someone living alone who was 65 years of age or older. The average household size was 2.4 and the average family size was 2.9.

In the county the population was spread out with 18% under the age of 18, 13% from 18 to 24, 38% from 25 to 44, 19% from 45 to 64, and 12% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 174 males. For every 100 females age 18 and over, there were 194 males.

The median income for a household in the county was $35,445, and the median income for a family was $43,207. Males had a median income of $24,888 versus $20,558 for females. The per capita income for the county was $14,629. About 5% of families and 9% of the population were below the poverty line, including 10% of those under age 18 and 10% of those age 65 or over.