There are 27 raw-steel producers in the United States. The seven largest hold 68 percent of the domestic steel market.

The seven largest steel companies, and their 1982 domestic market share, are: United States Steel Corp., 16.5 percent; Bethlehem Steel Corp., 14.3 percent; the LTV Corp., which owns Jones & Laughlin Steel Corp., 8.9 percent; National Steel Corp., 7.5 percent; Republic Steel Corp., 7.0 percent; Armco Inc., 7.0 percent, and Inland Steel Co. Inc., 6.8 percent.

Pennsylvania is the nation's leading steel producing state, responsible for about 20 percent of total 1982 domestic production. Indiana and Ohio rank second and third, respectively. Other major steel producing states include Illinois, Michigan and Alabama.

Steel is refined iron. Steelmaking has changed dramatically over the last several decades, moving from a slow, cumbersome procedure using open-hearth furnaces to more modern refining methods involving electric arc furnaces.

The most recent advance is a process called continuous casting, which converts molten steel into solid forms within 45 minutes, compared with 12 hours for conventional processing.

The U.S. auto industry is domestic steel's single largest customer, consuming about 15 percent of annual steel production. The construction industry is steel's second largest customer, followed by the oil and gas industry.