According to the 2000 census the five largest ancestry groups in Lincoln County are English (21%), German (18%), Irish (11%), Mexican (4%) and Italian (4%).
In the county, the population was spread out with 30.10% under the age of 18, 6.00% from 18 to 24, 21.90% from 25 to 44, 25.90% from 45 to 64, and 16.20% who were 65 years of age or older.