Start with the answer
Stationary Engineers and Boiler Operators pay in San Francisco-Oakland-Fremont, CA and Springfield, IL
The May 2025 BLS OEWS median for Stationary Engineers and Boiler Operators is $129,930 per year in San Francisco-Oakland-Fremont, CA. It is $117,590 per year in Springfield, IL. San Francisco-Oakland-Fremont, CA is 10.5% above Springfield, IL on the published median.
Both rows use SOC 51-8021 and the same annual wage metric. Median means the middle of each area's published wage spread. It is not one worker's pay. The larger median is not proof that one place gives a better job or a better result. It is one wage fact from one source period.
BLS lists 980 wage and salary jobs in San Francisco-Oakland-Fremont, CA and 60 in Springfield, IL. Those are survey job counts, not open posts. Read pay, job scale, local share, and price level as separate facts before you make a choice.
Evidence: bls-oews-may-2025 · Rule: same-soc-same-metric-pair · nominal-median-gap · employment-not-openings