=United States.=--The principal iron ores of the United States are the extensive pre-Cambrian hematite deposits of the Lake Superior region; the bedded fossiliferous ores of the Clinton type of Alabama and other southern states; the magnetite deposits of New York, northern New Jersey, and southeastern Pennsylvania; the limonite ores of the eastern and southern states; and the mixed hematite and magnetite ores of the West. The United States is the largest producer of iron ore in the world, and annually yields more than two-fifths of the world’s supply. More than 80 per cent. of the output comes from the Lake Superior district and most of the remainder from Alabama, New York, and Pennsylvania. In 1917 there were mined in the United States 75,000,000 tons of iron ore, of which 63,000,000 came from the Lake Superior region, 7,000,000 from Alabama, 1,000,000 from New York, and about 500,000 each from Pennsylvania, New Jersey, Tennessee, Virginia, and Wyoming; in 1918 the total production was 69,000,000 tons, of which 60,000,000 came from the Lake Superior district, 6,000,000 from Alabama, 900,000 from New York, 500,000 from Pennsylvania, and 400,000 each from Tennessee, Virginia, New Jersey and Wyoming. The following table shows the approximate reserves of iron ore in the principal districts of the United States: TABLE 14.--IRON-ORE RESERVES OF THE UNITED STATES IN GROSS TONS[30] Millions of tons. Lake Superior District (hematite) 3,500 Birmingham District (fossil hematite) 355 Tennessee and Virginia (fossil hematite) 100 Adirondack District (non-titaniferous magnetite) 40 Adirondack District (titaniferous magnetite) 90 Northern New Jersey and Southeastern New York (magnetite) 15 Southeastern Pennsylvania (magnetite) 40 Appalachian region (magnetite) 50 Northeastern Texas (limonite) 260 Western United States (magnetite and hematite) 100 Other Districts 150 ----- Total 4,700 [30] Kemp, J. F.: “The Iron-Ore Resources of the World,” Stockholm, 1910 (with minor revisions).