The "Iowa Model" for Redistricting


Nonpartisan Staff Draw Maps in Iowa--Legislature Votes on Them


Iowa state flagIowa stands alone in how it handles redistricting responsibilities.

Traditionally, state legislatures are responsible for redistricting. That is true for legislative redistricting in 35 states, and for Congressional redistricting in 40 states. Other states give this responsibility to a commission. See NCSL’s Redistricting Commissions: State Legislative Plans and Redistricting Commissions: Congressional Plans for details.

Iowa is among the states where the legislature has responsibility, but its method is unique: nonpartisan staff draw the lines with a nonpartisan approach. This webpage is a synopsis of how the “Iowa system” works. For more details, we recommend reaching out to Ed Cook with Iowa’s Legislative Services Agency (LSA).

Since 1980, Iowa’s districts have been drawn each decade by nonpartisan legislative staff.They follow a strict set of criteria, including a prohibition on the use of political data. Iowa is one of only a handful of states with such a prohibition. The prohibition is broad in scope, and encompasses the addresses of incumbents, the political affiliations of registered voters, previous election results and demographic information not required by the federal constitution.


The duty of drawing both legislative and congressional district lines falls to the state’s LSA. To assist it in fulfilling this duty, Iowa code calls for the creation each decade of a Temporary Redistricting Advisory Commission (TRAC), which provides guidance and advice to the LSA on certain redistricting matters when requested. Once the LSA finishes its proposed maps, TRAC conducts at least three public hearings on the maps and submits a report on the maps to the General Assembly. The entire process is quick—the LSA is required to deliver a redistricting plan in the form of a bill to the General Assembly no later than April 1 or within 45 days of the state receiving data from the Census in the year ending in 1 (2001, 2011, 2021).

After the submission of the first set of maps (congressional, Senate and House), the General Assembly gives the plan an up-or-down vote. The only permitted amendments are to correct errors in the LSA’s submitted plan. If the General Assembly rejects the plan, the LSA has 35 days to deliver a new plan which must address the reasons why the first plan was rejected. If this second plan is also rejected, the process repeats itself and the LSA has 35 days to deliver a third plan. Unlike the first two plans, this third plan may be amended in the same manner as any other bill, or the General Assembly may draft a plan of its own at that point.

If by Sept.1 of any year ending in “1” a legislative reapportionment bill fails to pass, the Iowa Constitution (Art. III, Sec. 35) directs the Iowa Supreme Court to adopt, or cause to be adopted, a redistricting plan for the General Assembly. There is no similar provision for congressional redistricting. If the legislature adopts its own plan independent of the three plans submitted by the LSA, it is subject to immediate review by the Supreme Court (Art. III, Sec. 36).

Since the enactment of this nonpartisan approach in 1980, each redistricting cycle has seen the enactment of a plan drawn by the LSA. The first plan was enacted in 1991 and 2011; the second plan was enacted in 2001; and the third plan was enacted in 1981 without amendment.

Iowa’s unique plan is statutory, not constitutional. Thus, it is always subject to repeal. 

Nesting Districts

In addition to the legal requirements mentioned above, the order and manner of setting up districts is based on “nesting.” Iowa staff first draw the Congressional district boundaries, making sure population deviation is as small as possible and the compact formula is as tight as possible.  Then, staff works on the legislative districts. Iowa has 50 senate districts, and 100 state house districts, and “nesting” is required by law for these legislative seats. That means that each Senate district has exactly two House districts within its boundaries. To the extent possible, these districts are nested within the U.S. House districts, although this is not required by law. In the 2011 cycle, Congressional boundaries were crossed just twice when drawing legislative districts.

The result is that districts are compact, and that voters have more continuity in their representation from the state House, through the state Senate, to the U.S. House.

Additional Resources