Missouri, Iowa, Wisconsin, and Lake Michigan; admitted to the Union, Dec. 3, 1818: number of counties, 102; capital, Springfield; area, 56,650 square miles; pop. (1890) 3,826,351; (1900) 4,821,550; (1910) 5,638,591; (1920) 6,485,280.
Topography.—The surface of the State is generally flat, rising in an inclined plane from a depression of 300 feet near Cairo, to an elevation of 820 feet in Jo Daviess county. A spur of the Ozark Mountains crosses the S. part of the State. The principal physical features of the State are the great prairies or natural meadows, from which Illinois derives its popular name, the “Prairie State.” The river system of Illinois is the most extensive in the Union. The Mississippi forms its entire W. boundary, and its great E. tributary, the Ohio, with its affluents, the Illinois, Wabash, Kankakee, Des Plaines, Kaskaskia, Mackinaw, Sangamon, Vermilion, and their numerous tributaries, form a water system of over 280 streams. The Illinois river broadens out into an extensive basin, known as Lake Peoria in the central part of the State. This, with Lake Pishtaka in the extreme N. E., comprises the lake system of Illinois. There are numerous natural points of interest, among them being Starved Rock, a mass of sand and limestone rising abruptly to a height of 160 feet; Fountain Bluff, 6 miles in circumference and 300 feet high; and a large cave in Hardin county, on the Ohio river, formerly a noted retreat for river pirates.
Geology.—The N. part of the State shows Silurian origin, with Tertiary and Post-Tertiary formations in the S., and Devonian strata in the S. hills. Geological research seems to show that the Great Lakes were once connected with the Gulf through the channels of the Illinois and Mississippi rivers, the whole region being an immense lake. Fresh water shells have been found in the Post-Tertiary clays and sands on the lake shore and marine shells are found in the soil of the prairies. Along the Mississippi river are steep bluffs of lime and sandstone, called from their form, Castle Rocks.
Mineralogy.—Bituminous coal is found in a field 375 miles long by 200 miles broad, usually in the form of cannel coal, though some excellent smelting coal is also found. The coal production of the State in 1918 was 91,263,000 tons, an increase of about 5,000,000 tons over 1917. The production of pig iron in the State in 1918 was 3,409,876 tons valued at $105,415,030. The production of natural gas in 1917 was 4,439,016 M. cubic feet, valued at $479,072. The production of petroleum in 1917 was 15,776,850 barrels, valued at $31,358,069. Other important mineral products are cement, of which about 5,000,000 barrels are produced annually; coke; mineral waters; sand and gravel; and clay products. The total value of the mineral products in 1917 was $216,914,229.
Soil.—The soil is generally black, light, rich, and warm, and free from stones and pebbles, though in places it is mixed with a siliceous sand. It is exceedingly fertile. In some places the loam has a depth of 25 feet. The prairie lands consist of the original diluvial sediment, overlaid with decomposed vegetable matter. The “American Bottom,” 5 miles in width and extending 90 miles along the Mississippi, has been cultivated ever since the first settlement, and its fertility still seems inexhaustible. The most abundant forest trees are the oak, black walnut, ash, hickory, sugar maple, locust, elm, linden, tulip, buckeye, poplar, beech, yellow pine, cypress, cedar, pecan, sycamore, cottonwood, and black birch.
Agriculture.—Illinois is one of the foremost States in agriculture. The fertility of its soil makes it especially adaptable for the raising of cereals, farm and garden vegetables, and fruit. Among its chief products are raspberries, strawberries, cherries, plums, peaches, grapes, apples, potatoes, tobacco, maple sugar, hops, flaxseed, and broomcorn. The production and value of the principal crops in 1919 were as follows: corn, 301,000,000 bushels, valued at $391,300,000; oats, 123,060,000 bushels, valued at $86,142,000; wheat, 65,675,000 bushels, valued at $137,918,000; hay, 4,810,000 tons, valued at $102,934,000; potatoes, 8,060,000 bushels, valued at $15,798,000.
Manufactures.—There were in 1914 18,388 manufacturing establishments in the State, employing 506,943 wage earners. The capital invested amounted to $1,943,826,000, and the wages paid to $304,910,000. The value of materials used was $1,384,184,000, and the value of the finished product was $2,247,323,000.
Banking.—On Oct. 31, 1919, there were 475 National banks in operation, having $79,415,000 capital, $25,069,286 in outstanding circulation, and $27,947,200 in United States bonds. There were also 905 State banks with $101,189,000 capital, and $67,135,000 surplus; 174 private banks, with $3,366,000 capital and $904,000 surplus. In the year ending Sept. 30, 1919, the exchanges at the United States clearing house, at Chicago,
