Modern-day Pottawattamie County evolved out of the Pottawattamie Purchase of 1847. It was named for the Indian tribe that once possessed the Iowa Territory. The name is an Indian term meaning "Blowers of Fire," "Keepers of the Council Fires," or "Makers of Fire."  The county was established in 1837 and originated in 1847.

The county is the second largest in area in Iowa and has two courthouses -- one in Council Bluffs and another in Avoca. However, Pottawattamie has only one county seat: Council Bluffs.

County commissioners selected Kanesville and Pleasant Grove as potential sites for the county seat and on April 7, 1851 all but seven votes were cast for Kanesville, previously known as Hart's Bluff and Miller's Hollow. It was changed to Council Bluffs in 1853.

The first real courthouse was completed in Council Bluffs in 1868. The two-story brick and stone building cost $50,000 to complete. Prior to this the county offices were housed in Hyde's New Hall.

Early in 1884, only 16 years later, there was the need for a new courthouse. The old one was unsafe and county offices lacked sufficient space. A bond issue was voted on and passed to construct a $150,000 courthouse and $30,000 jail. The winning bid came from Eckel and Mann for $136,800 and the old courthouse was sold for $3,000. County offices were then held in the Masonic Temple until the second courthouse was completed.

In December 1972 it was discovered that the 87-year-old building was sinking into the ground, at rate of about 2 inches a month. On August 22, 1973, voters approved a $2.5 million bond issue for a new county courthouse and jail. Additional funds for the $4.5 million project were obtained from the federal government.

The original town plat of Avoca was made in 1869, the same time when the railroad reached the area. The second courthouse appeared in Avoca around January 1885. This courthouse houses the offices of the county clerk, sheriff and magistrate court.