Big River Steel is considering a relatively small new mill in Brownsville. Not definite, and at $1.6 Billion, its not a huge plant. Not a primary ingot mill- a plate mill.
Steel dreams: Port awaits decision on mill location - Valley Morning Star : Local News
Nucor, which has been consistently building new mills and adding on to existing ones since the late 1960s, has a new mill planned for somewhere in the midwest. Again, a plate mill.
Smaller than the Big River mill, at approx 400 employees.
Nucor to Build State-of-the-Art Plate Mill
Cliffs is in the process of getting a HBI mill going in Cleveland. HBI- Hot Briquetted Iron- is a technology for making iron ore into feedstock for EAF (Electric Arc Furnace) Steel mills- EAF is what somebody was calling "remelt"- but you can put a lot of different things into an EAF mill, including scrap, but also including iron ore, assuming its in the right form.
Nobody has built a new mill that makes steel from taconite in a long time in the USA, and, most likely as EAF continuous casting mills continue to get better, nobody will.
Especially as Cliffs gets more capacity going for HBI.
Cleveland-Cliffs Inc. - About Us - Operations
But, no, Trump is not telling the truth.
All the current construction of new mills and the ongoing rebuilding of existing mills is nothing new- its been going on for decades, steadily. The USA, today, makes as much steel (actually a bit more) than we did at the peak of WW2. We make 80 to 100 million tons a year, depending on demand. Its cheaper to make it here, as opposed to shipping it here.