Highest salary at St Charles County in year 2020 was $203,114. Number of employees at St Charles County in year 2020 was 1,100. Average annual salary was $53,435 and median salary was $51,367. St Charles County average salary is 14 percent higher than USA average and median salary is 18 percent higher than USA median salary. From 2019 to 2020, the average salary of employees at this employer increased 2.7 percent, the median salary increased 3.1 percent.