Since the 1880s, there have been major changes in the location or nature of Iowa's 4th Congressional District. From 1886 until 1941, the district was made up of largely rural counties in northeastern Iowa, including the easternmost five counties in the northernmost two rows (and, during the 1930s, Buchanan and Delaware counties from the third row). During that era, the district included areas from Mason City east to the Mississippi River.
In 1941, Iowa's 5th Congressional District (made up of rural counties in southern Iowa) was renumbered as Iowa's 4th Congressional District, and counties in the old 4th District were placed in the 3rd District and the 2nd District. (In 1942, 4th District incumbent, Henry O. Talle, would defeat the 2nd District incumbent William S. Jacobsen in the new 2nd Congressional District). From 1941 until 1960 the 4th Congressional District included the central five counties of each of the two southernmost tiers, plus four counties between Des Moines and Iowa City (Mahaska, Keokuk, Jasper and Poweshiek). Because the new 4th Congressional District was identical to the old 5th Congressional District, 5th District incumbent Republican U.S. RepresentativeKarl M. LeCompte, was elected in 1942 and in the next seven races. In 1958, when LeCompte did not run, Democrat Steven V. Carter defeated Republican John Kyl. A recurrence of cancer would claim Carter's life before the end of his only term, and Kyl won the special election and next general election. In 1961 the 4th Congressional District was expanded to include five central Iowa counties - Warren, Marion, Marshall, Tama and Benton - but retained its rural character. Except for the 1964 election, Kyl won each race during this period.
The rural character of the district was changed when most of its territory was merged with the Des Moines-based 5th District of Democratic incumbent Neal Smith after the 1970 census. Polk County (home to Des Moines and most of its suburbs) was added, while most of the rural counties were taken out. Smith defeated Kyl in the 1972 congressional election. The district became even less rural in 1981, when Story County (home of Ames) was added, and other rural counties were taken out. Smith would hold the seat until his 1994 defeat by Republican Greg Ganske.
The 2001 remap made the 4th district a north-central Iowa district. It could not be said to be the successor of any of the previous districts. It was a primarily rural district, though it included Ames and Mason City. It did not include any of the state's nine largest cities, and only four of the twenty largest Iowa cities. The plan went into effect in 2003 for the 108th U.S. Congress. The prior redistricting plan was effective from 1993-2003.
For the 2012 elections, the Iowa Legislature passed a plan that went into effect in 2013 for the 113th U.S. Congress. The prior redistricting plan was effective from 2003-2013. The district now covers the northwest corner of the state, and contains most of the territory that had been in the 5th district prior to redistricting.