It looks like they haven’t decided yet:
Steel Dynamics to build new organic flat roll steel mill costing $1.7B-$1.8B
FTA: Steel Dynamics (NASDAQ:STLD) announces plans to spend $1.7B-$1.8B on construction of a new electric arc furnace flat roll steel mill in the southwestern U.S. to serve the southern U.S. and the underserved Mexican flat roll steel market.
STLD expects the facility will have an annual production capacity of ~3M tons with the capability to produce the latest generation of advanced high strength steel products; the project will include value-added finishing lines, including a galvanizing line with an annual capacity of 450K, and a paint line with an annual coating capacity of 250K tons.
Upon final site selection and obtaining required environmental and operating permits, STLD expects to begin construction in 2020 with operations starting in H2 2021.
Thanks, gub.