Description of the industry. This industry consists in the conversion of pig iron and scrap into steel and the rolling of iron and steel. In many cases the processes of conversion and rolling (and in some cases further fabrication) are performed in the same plants, and in such cases the value of products represents only the finished products. For censuses prior to 1939, the production of steel castings was treated as part of the "Steel works and rolling mills" industry, but for 1939, "Steel castings" was set up as a separate industry. A special tabulation of the 1937 and 1929 figures was prepared to show comparable figures. Statistics on the total production of steel castings will be found in a report entitled "Iron and steel foundry products."

Some steel plants, however, produce crude steel or partly rolled steel, which is used as a material by other steel plants, and this causes some degree of duplication in the figures for value of products and cost of materials. The amount of duplication in the total value of products for the industry cannot be accurately determined, but it is equal to the sum of (1) the major part of the value ($272,467,476) of the ingots and semifinished rolled products (except for forgings) made for sale and for transfer to other plants operated under the same ownership or by affiliated companies and (2) a considerable but indeterminable part of the value ($204,491,714) of the "interplant transfers" of direct steel castings, forgings, and finished rolled products made in certain plants and transferred to other plants, operated under the same ownership or by affiliated companies, for use as materials in further manufacture. All but a small portion of the ingots and semifinished rolled products manufactured for sale and for interplant transfer, and to a large extent the steel castings, forgings, and finished rolled products transferred to other plants, are used as materials within the industry, and therefore their values are again included in the total value of finished products. The tonnage produced and consumed in different departments of the same plant does not carry an assigned value, so no duplication arises from this source.

In many establishments the manufacturing processes are carried beyond the rolling stage. For example: Tin-dipping departments are operated by some of the

black-plate rolling mills, pipe-and-tube departments by skelp mills, and wire-drawing departments by wirerod mills. For this reason the industry overlaps a number of others and the products include certain commodities identical in character with the primary products of other industries. (See "Tin plate and terneplate," p. 195, the table "Principal manufactures from rolling-mill products," p. 189, and the report for "Wire drawn from purchased rods," p. 213.)

A large part of the pig iron used as a material by steel works is delivered, mostly in a molten state, by blast furnaces operated in conjunction with the steel works. works. (See "Relation of blast-furnace products and steel works and rolling mills products," p. 180.)

Detailed statistics of products.-Statistics relating to individual products or classes of products are given in tables 3 to 9, inclusive. The presentation in table 3 is made under eight general headings, namely: Unrolled steel; semifinished rolled products; finished hot-rolled products and forgings; scrap iron and steel; cinder and scale; miscellaneous products other than iron or steel; custom work and repairing; products further manufactured from finished rolling-mill and foundry products.

Table 3 has been prepared in such form as to show separately the tonnage produced and consumed in the same works, the tonnage produced and transferred to other plants under the same ownership or to plants operated by affiliated companies, and the tonnage produced for sale. The tonnage transferred to other plants carries an assigned value, but no value is assigned to the tonnage produced and consumed in different departments of the same works.

In many cases rolling mills operate departments for the conversion of rolling-mill products into pipes and tubes, bolts and nuts, cut nails and spikes, and other finished iron and steel products. These products, when manufactured in plants other than departments of rolling mills, although in some cases under the same ownership, are classified in other industries. The total output of these products, by kind, quantity, and value, as reported for all industries, is shown, so far as practicable, in table 4, p. 189.

Tin plate and terneplate are manufactured almost exclusively and wire and wire products are made to a

463396-42- -13

considerable extent in departments operated in connection with rolling mills. Statistics showing the total production of wire and wire products made both in wire departments of rolling mills and in establishments covered by separate industry classifications, will be found in a report covering the Wire Products subgroup of industries. For production of tin plate and terneplate, see page 195.

The schedule form used in canvassing the establishments in the "Steel works and rolling mills" industry called for tonnage units of 2,240 pounds while certain trade organizations collecting similar data reported tonnage in units of 2,000 pounds.

2 See GENERAL EXPLANATIONS-Definition of establishment.

See GENERAL EXPLANATIONS-Persons engaged-general classification.

4 See GENERAL EXPLANATIONS-Wage earners and wages.