Ottawa City (1990 pop. 17,451), seat of La Salle co., N central Ill., at the confluence of the Fox and Illinois rivers, in a fertile farm area; inc. as a city 1853. The city has diversified agriculture and manufactures glass, tools, building materials, and automobile parts. Points of interest include the site of the first Lincoln-Douglas debate (1858) and Fort Johnson (1832). Several state parks are in the area, and scenic attractions along the rivers draw many visitors.