Mine-to-Mill in the Upper Midwest: An Economic and National-Security Assessment of Mesabi Metallics' Proposed $18 Billion Minnesota–Iowa Electric-Arc-Furnace Steel Supply Chain

This dissertation develops and applies a transparent, reproducible framework for the ex ante evaluation of the economic claims surrounding Mesabi Metallics' announced $18 billion mine-to-mill steel supply chain, which would link a taconite and direct-reduction-grade pellet operation at Nashwauk, Minnesota, to a proposed steel complex in Lee County, Iowa. Because the program is young—Iowa construction had not begun and the Nashwauk plant recorded only its first production on September 17, 2026—the study is explicitly ex ante and estimates no post-treatment effects. Using only publicly available data and version-controlled code, I classify every assertion under a three-tier evidentiary standard, model regional effects through conditional input–output scenarios, run pre-period causal diagnostics, map feedstock and resilience balances, and build an expected-present-value fiscal model. Six hypotheses were evaluated at the first measurement date, October 5, 2026. Verified committed investment was $0.00 billion against the announced $18 billion, at most 8.6% even when every claim-tier financing item is counted (H1, supported). Two-state modeled output reached $80.79 billion, about 85% of the promoted $95 billion, a figure only 26.0% of Monte Carlo draws exceeded (H2, partially supported). Because no post-treatment period yet exists, local employment effects are not testable; Lee County shows a marginal pre-trend (p = 0.047) and a minimum detectable effect near 1,737 jobs (H3, not yet testable). Seven million metric tons of pellets cover only 47–81% of announced capacity at high direct-reduced-iron charge rates (H4, supported). Domesticity of ore-based metallics rises by roughly 4.9 Mt while single-site concentration increases (H5, supported). The expected present value of net public benefit is −$45 million at a 5% discount rate, turning positive only if local tax capture reaches at least 8.2% (H6, partially supported). The study shows that the program's promotional magnitudes substantially exceed what public evidence presently supports, and it leaves policymakers a reproducible basis for monitoring the project as treatment events unfold.