Missouri's Changing Legislative Boundaries

While the decennial US Census is used to determine the distribution of funds for, among other things, infrastructure, education, and healthcare, the creation, elimination, and alteration of legislative districts may very well be the single most important change based on updated population estimates. Changes to the districts that determine the composition of the US House of Representatives typically (and understandably) receive the majority of attention in the wake of a new Census, but state legislatures are just as malleable and changes to those boundaries have a much bigger impact on local politics.

The maps featured in this application highlight the changes to both the Missouri House and Senate boundaries after the 2020 US Census. Each chamber is represented by its own swipe map, the Missouri House first and the Missouri Senate second. The red outlines on each map (the left side of the swipe tool, in this case) indicate the new, post-2020 districts while the blue outlines (the right side) represent the previous boundaries. Left-clicking on any district will open a pop-up window identifying the district number and, for the newer boundaries, the current office holder.


Changes to the Missouri House of Representatives Districts

While some parts of some House of Representatives districts stayed intact (the 154th District in the middle of Missouri's southern border remained surprisingly unchanged, for example), it is fairly easy to see that there were significant changes based on the latest census. The very center of the map is an excellent example of the boundary shift. Before the census (illustrated by the blue outlines) the Mid-Missouri region is a tangle of unrecognizable regions. After the census, though, the boundaries of both Boone and Cole County are very plainly clear.

Changes to the Missouri Senate Districts

Like the House of Representatives, Missouri's Senate also experienced significant changes to its district boundaries. The post-2020 version of the 13th District, located in the St Louis area, is fairly similar to its earlier footprint, but it is the exception rather than the rule. Once again, one need only look to Mid-Missouri for an example of the extreme shift in boundaries. Where Caleb Rowden previously represented both Boone and Cooper Counties via the Senate's 19th District, he now represents only the people of Boone County.


While it is obviously far too early to know how the redrawn legislative districts will change the direction of Missouri politics, it is an undeniable fact that the new maps create a whole new political ballgame. Some lawmakers now represent vastly different collections of constituents while others faced more competitive races in order to hold on to the office they already occupied[1], and all of these changes can be traced back to the decennial census. Whatever Missouri's future holds, the many changes to its legislative districts are a testament to the importance of the US Census.