In 1945, the USA produced 57 percent of world steel output.
Today it is 5 percent
Our steel industry declined for one big reason: the three major waves of steel consumption ended — railroads (mostly built out by the 1920s), highway bridges (during the construction of the Interstate Highway System in the 1950s and 1960s) and automobiles (from the 1950s until the 1980s when much of the steel was displaced by lightweight plastics and composite materials in cars).