ALTON, a town in Madison county, Illinois, United States, stands on a high bluff on the left bank of the Mississippi, 21 miles above St Louis, and 3 above the mouth of the Missouri. It is a place of considerable importance, and carries on a thriving export trade in the produce of the surrounding country - grain, hay, fruit, coal, and lime. It has an excellent wharf, and good means of communication by railway, the two great lines from Chicago and Indianopolis having their junction at Alton. The town contains a Roman Catholic cathedral, about ten other churches belonging to various sects, and several schools. It has also a printing trade, with daily and weekly newspapers. Population in 1870, 8665.