BLS metro-level wage data places Engine and Other Machine Assemblers pay in St. Louis, MO-IL at a median of $51,920 per year ($24.96/hr/hour), drawn from the OEWS May 2025 release for this Metropolitan Statistical Area. Compared to the national median of $53,710, St. Louis pays 3% below, which typically tracks with a lower local cost of living or smaller specialized-employer cluster. Approximately 120 engine and other machine assemblerss are employed across the St. Louis MSA in SOC 51-2031.

The St. Louis pay distribution spans from $42,240 at the 10th percentile to $63,200 at the 90th — a 1.5× spread that reflects experience tenure, specialization, employer size, and the difference between public-sector, nonprofit, and private-sector compensation inside the metro. The 25th percentile sits at $45,340 and the 75th at $62,460, so half of St. Louis-based engine and other machine assemblerss earn within that middle band.

Metro figures capture where you actually work, not just where you live — which matters for commuters. BLS draws metro boundaries from the OMB MSA definitions, so St. Louis, MO-IL covers the central city plus outlying counties tied to the metro economically. Remember that OEWS wages reflect base pay only: employer-provided health insurance, retirement matches, stock options, signing bonuses, overtime, and tips are excluded and can add 20-40% to real total compensation. Before using this metro median as a negotiation anchor, triangulate against the same occupation's national profile (linked below), its state-wide MO data, and peer-metro comparisons — a median is a starting point, not a ceiling.