Integration was the watchword as the various processes were brought together by large corporations, from mining the iron ore to shipping the finished product to wholesalers. The typical steelworks was a giant operation, including blast furnaces, Bessemer converters, open-hearth furnaces, rolling mills, coke ovens and foundries, as well as supported transportation facilities. The largest ones were operated in the region from Chicago to St. Louis to Baltimore, Philadelphia and Buffalo.  Smaller operations appeared in Birmingham, Alabama, and in California.
The industry grew slowly but other industries grew even faster, so that by 1967, as the downward spiral began, steel accounted for 4.4% of manufacturing employment and 4.9% of manufacturing output. After 1970 American steel producers could no longer compete effectively with low-wage producers elsewhere. Imports and local mini-mills undercut sales.
Per-capita steel consumption in the U.S. peaked in 1977, then fell by half before staging a modest recovery to levels well below the peak.
Most mills were closed. Bethlehem went bankrupt in 2001.  In 1984, Republic merged with Jones and Laughlin Steel Company; the new firm went bankrupt in 2001.  US Steel diversified into oil (Marathon Oil was spun off in 2001). Finally US Steel reemerged in 2002 with plants in three American locations (plus one in Europe) that employed fewer than one-tenth the 168,000 workers of 1902. By 2001 steel accounted for only 0.8% of manufacturing employment and 0.8% of manufacturing output.
The world steel industry peaked in 2007.  That year, ThyssenKrupp spent $12 billion to build the two most modern mills in the world, in Alabama and Brazil.  The worldwide great recession starting in 2008, however, with its heavy cutbacks in construction, sharply lowered demand and prices fell 40%.  ThyssenKrupp lost $11 billion on its two new plants, which sold steel below the cost of production.  Finally in 2013, ThyssenKrupp offered the plants for sale at under $4 billion.