[4][5] The first county seat was established at the town of Iroquois in 1837, though no official buildings were constructed there and offices were rented.

Several other sites for the county seat were examined, and in 1839 it was moved to Middleport; a court house and jail were built there.

The northern border of the county is about 60 miles (97 km) south of the city of Chicago.

Sugar Creek, further to the south, also flows from the east to the west, entering from Indiana east of Stockland; it passes through the south edge of Milford, is joined by Mud Creek coming up from the south, and winds to the north past the village of Woodland and meets the Iroquois River near Watseka.

Amtrak provides intercity passenger rail service on the Illini and Saluki at Gilman station.

Interstate 57 passes through the west part of the county on its route between Champaign and Chicago.

From north to south, it passes through or near Chebanse, Clifton, Ashkum, Danforth, Gilman, Onarga, Buckley, and Loda.

The Toledo, Peoria and Western Railway operates a line that begins in Peoria and runs from east to west through Iroquois County, passing through Gilman and Watseka and continuing into Indiana.

A Canadian National Railway line runs nearly parallel with Interstate 57 on its way to Chicago.

[13] As of the 2010 United States census, there were 29,718 people, 11,956 households, and 8,175 families residing in the county.

[25] Media related to Iroquois County, Illinois at Wikimedia Commons