Climate.- Illinois lies between the isotherm of 55 on the south and 47 on the north. It is notable for extremes of temperature. Warm winds sweeping up the Mississippi Valley cause extreme heat; the Arctic winds from the north, unblocked by mountains, cause the ex tremes of cold. The range of extremes is greater in the north than in the south. Thus at Winnebago extremes have ranged from 26° F. to 110° F., and at Cairo from 16° F. to 106° F. The mean temperature for Springfield, near the central part of the State, is 52° F. The variation is about 2° F. for each degree of latitude. The State is well watered. The number of inches of rainfall is about 40 for the south end of the State, but it decreases to about 34 in the north. The mean annual snow fall increases from about 12 inches in the south to about 40 in the north. The source of the rainfall is chiefly the revolving storms from the northwest. At Cairo in the south, except during February, the prevailing winds are southerly, and as far north as Springfield they are southerly from April to January. Through out the northern half of the State, except along the shore of Lake Michigan, where they vary from northeast to southwest, the winds are mostly from the west or northwest from Octo ber to March, and very variable for the rest of the year.
Population.- In 1810, one year after its or ganization as a Territory, the population of Illi nois was 12,282; in 1820, two years after its ad mission as a State, its population was 55,211, and in rank it was the 24th State in the Union; in 1830, its population was 157,445 and its rank the 20th; in 1840, its population was 476,183 and its rank the 14th; in 1850, its population was 851,470 and its rank the 11th; in 1860, its popu lation was 1,711,951, and its rank the 4th; in 1870, its population was 2,539,891 and its rank the same as in 1860; in 1880, its population was 3,077,871 and its rank still 4th; in 1890 its population was 3,826,351 and its rank the 3d; in 1900, its population had increased to 4,821,550 while its rank remained the same; in 1910. its population was 5,638,591 and its rank was still third. An analysis of the population as shown by the census of 1910 reveals the following interest ing facts; 2,600,555, or 46.1 per cent, were native whites of native parentage; 1,723,847, or 30.6 per cent, were native whites of foreign or mixed parentage; 1,202,560, or 21.3 per cent, were foreign born whites; and 109,049, or 1.9 per cent, were negroes. Of the total native population, 76.8 per cent were born in Illinois, and 23.2 per cent outside the State. Of the total stock of foreign origin, Germany contributed 34.7 per cent; the Scandinavian countries, 11.3; Ireland, 11.3; Austria, 9.6; Russia, 7.8; England, 5.8; Italy, 4; Canada, 3.7; Scotland, 1.8; Hungary, 1.8; and Holland, 1.1. Of the foreign born white population, Germans composed 26.5 per cent; Austrians, 13.6; Rus sians, 12.4; Swedes, 9.6; Irish 7.8; Italians, 6;
English, 5; Canadians, 3.7; flungarians, 3.3; Norwegians, 2.7; all other countries, 92. Of the negro population, 66.8 per cent were born outside of the State. In most of the 102 coun ties the proportion of foreign born whites is small, being less than 5 per cent in 40 coun ties, and over 25 per cent in only six. Over two-thirds of the foreign born whites live in Cook County. Their percentage is 28.7 in the urban population and 9.5 in the rural; the percentage for the negroes is 2.5 in the urban and 1.1 in the rural districts. The male popu lation predominates. In 1910 there were 2,911, 674 males to 2,726,917 females or 106.8 males to 100 females; in 1900, the ratio was 105.3 to 100. Among native whites, in 1910, the ratio was only 101.5 to 100, but among foreign born whites it was 127.3 to 100. In the urban population there were 104.9 males to 100 females, and in the rural 109.9. These people occupied 1,006, 848 dwellings and the total number of families was 1,264,717 or 125.6 families to 100 dwellings. The average number of persons per dwelling was 5.6, and the average number per family was 4.5. Cook county claimed 2,405,233 persons, Saint Clair County ranked next with 119,870, and Peoria County was third with 100,255. Taking the State as a whole, it had 100.6 peo ple to the square mile in 1910, as compared with 86.1 in 1900, and 68.3 in 1890. The population according to census estimates increased from 5,638,591 in 1910 to 6,152,257 in 1916, and its density, consequently, from 100.6 to 109.8 Cities.- In 1910, 61.7 per cent of the entire population resided in incorporated places hav ing 2,500 inhabitants or over; in 1900, the per cent was 54.3. In the same years the figures for the United States as a whole stood 46.3 and 40.5; for the New England States 83.3 and 79.9; for Rhode Island, 96.7 and for Massachusetts, 92.8 and 91.5. According to the last census there were 32 incorporated places in the State which had a population of over 10,000. Chicago had 2,185,283; 11 others had over 25,000 but less than 100,000; the rest had between 10,000 and 25,000. On 1 July 1916 the estimated population of the five leading cities was : Chicago, 2,497,722; East Saint Lows, 74, 708; Peoria, 71,458; Springfield, 61,120; Rock ford, 55,185. In July 1915 some of the other cities ranked as follows: Decatur, 38,526; Joliet, 37,472• Quincy, 36,764; Aurora, 33,613; Danville, 31,554; Evanston, 28,012i Elgin 27, 844; Bloomington, 27,054; Moline, 26,927; Galesburg, 23,923; Alton, 22,483; Belleville, 21,144; Waukegan, 19,471; Freeport, 19,293; Cicerotown, 19,102; Cairo, 15,593; Jacksonville, 15,456; Kankakee, 14,190; Champaign, 14,171; Kewanee, 13,517; Mattoon, 12,400; La Salle, 12,110; Lincoln, 11,685. Within the last few years the following cities have probably passed the 10,000 mark: Canton, Monmouth, Maywood, Ottawa, Urbana, Mount Vernon and De Kalb.