Highest salary at City of O'Fallon in year 2023 was $192,491. Number of employees at City of O'Fallon in year 2023 was 492. Average annual salary was $61,947 and median salary was $60,983. City of O'Fallon average salary is 32 percent higher than USA average and median salary is 40 percent higher than USA median salary. From 2022 to 2023, the average salary of employees at this employer increased 8.2 percent, the median salary increased 7.4 percent.