Deposits of lead and zinc have been discovered and worked in Jo Daviess county, near Galena and Elizabeth, in the N.W. part of the state. A southern district, including parts of Hardin, Pope and Saline counties, has produced, incidentally to fluorspar, some lead, the maximum amount being 176,387 lb. from the Fairview mine in 1866-1867. In 1905 the zinc from the entire state was valued at $5,499,508; the lead product in 1906 was valued at $65,208. Sandstone, quarried in 10 counties, was valued in 1905 at $29,115 and in 1906 at $19,125. Pope and Hardin counties were the only sources of fluorspar in the United States from 1842 until 1898, when fluorspar began to be mined in Kentucky; in 1906 the output was 28,268 tons, valued at $160,623, and in 1905 33,275 tons, valued at $220,206. The centre of the fluorspar district was Rosiclare in Hardin county. The cement deposits are also of value, natural cement being valued at $118,221 and Portland cement at $2,461,494 in 1906. Iron ore has been discovered. Glass sand is obtained from the Illinois river valley in La Salle county; in 1906 it was valued at $156,684, making the state in this product second only to Pennsylvania and West Virginia (in 1905 it was second only to Pennsylvania). The value of the total mineral product of the state in 1906 was estimated at $121,188,306.[2] _Communications._--Transportation facilities have been an important factor in the economic development of Illinois. The first European settlers, who were French, came by way of the Great Lakes, and established intimate relations with New Orleans by the Mississippi river. The American settlers came by way of the Ohio river, and the immigrants from the New England and Eastern states found their way to Illinois over the Erie Canal and the Great Lakes. The first transportation problem was to connect Lake Michigan and the Mississippi river; this was accomplished by building the Illinois & Michigan canal to La Salle, at the head of the navigation on the Illinois river, a work which was begun in 1836 and completed in 1848 under the auspices of the state. In 1890 the Sanitary District of Chicago undertook the construction of a canal from Chicago to Joliet, where the new canal joins the Illinois & Michigan canal; this canal is 24 ft. deep and 160 ft. wide. The Federal government completed in October 1907 the construction of a new canal, the Illinois & Mississippi, popularly known as the Hennepin, from Hennepin to Rock river (just above the mouth of Green river), 7 ft. deep, 52 ft. wide (at bottom), and 80 ft. wide at the water-line. This canal provides, with the Illinois & Michigan canal and the Illinois river, an improved waterway from Chicago to the Mississippi river, and greatly increases the commercial and industrial importance of the "twin cities" of Sterling and Rock Falls, where the Rock river is dammed by a dam nearly 1500 ft. long, making the main feeder for the canal.