Highest salary at St Clair County in year 2017 was $166,506. Number of employees at St Clair County in year 2017 was 864. Average annual salary was $45,072 and median salary was $42,428. St Clair County average salary is 4 percent lower than USA average and median salary is 2 percent lower than USA median salary. From 2016 to 2017, the average salary of employees at this employer increased 4.1 percent, the median salary increased 2.4 percent.