Voting Districts

Congressional Voting Districts

Congressional voting districts are the land areas assigned to each of the 435 seats in the US House of Representatives. The number of seats is fixed whilst the population varies from congress to congress. To ensure that each seat represents the same amount of people, boundaries of districts have to be redrawn on a regular basis.

The basis for knowing how many people live in the US is the Decennial Census. As the name implies, it takes place every ten years, on the zero year. Federal law requires all residents of the US (note: not voters, but residents) as well as US citizens and permanent residents overseas to fill out a census form. Those who do not are visited by enumerators and census data are taken at their places of residence.

Census-taking begins in January and ends in the Fall. After that, Bureau of Census statisticians work to produce the final numbers of people for each address in the US. The results are then used during the following year as the basis for the process of reapportionment.

Apportionment

The US Constitution stipulates that each state gets two senators regardless of population, whilst the House of Representatives ("Congress") is based on proportional representation. For a long time, the number of electoral districts in the US has been 435, matching the number of seats in Congress. Each seat is occupied for two years by an elected federal representative, and most of these are from either the Democratic or Republican party.

Every two years (even years only except for special elections), elections are held. If the representative (congressperson) does not run for reelection, the seat is vacated. Otherwise, the incumbent runs for reelection and either wins, keeping the seat, or loses, giving it up to someone of their own party or another party. Just like in the Senate, there are no term limits (Senate terms, however, are six years).

The stakes are very high in this process because lawmakers vote on policy that affects not only their local electoral districts but also the state and nation at large, and the entire world.

Reapportionment

States gain and lose population over the course of each decade, and areas within states gain and lose people as well. Each seat has to represent around 761000 people (again note: not just voters) according to the 2020 Census, a number that grows every 10 years as the US population grows. The boundaries of the districts have to change to keep up with this.

The first step is Congressional reapportioning of seats in states gaining or losing a certain number of people. After 2020, this meant that Texas got two new seats (its population grew a lot), while Montana, Colorado, Florida, Oregon, and North Carolina got one new seat each (their populations all grew). Logically, that meant that there had to be some losers. These were: California; Illinois; Michigan; New York; Ohio; Pennsylvania; West Virginia, all states with shrinking populations.

Redistricting

The next step is redistricting. States must redraw their electoral district lines in time for the midterm election cycle, which most recently took place in late 2022.

This is a complex and fraught process. Manipulating voting districts, as we describe in detail below, is a major issue. The two principal US political parties (Republican and Democrat) have much to gain and much to lose in this process. Let's see how.

States have various ways of redistricting federal congressional districts (note: they also reapportion and redistrict state congressional districts, but that happens only at the state level). Typically, states appoint a bipartisan group of Democrats and Republicans who task out the actual demographic and geographic work to experts. Nowadays, extremely precise lines can be drawn because of the exact geolocation of addresses available through the GIS used by the Census Bureau.

The result is a new state map that has to be approved by the state as well as the federal government. Independent groups, often linked to a political party, may sue to stop the certification of the new district lines, and state or federal courts may block the new map as well. This is because of perceived manipulation of electoral district lines that can cause a bloc of voters to become disenfranchised or, in some other way, lose influence at the expense of another group.

Voting Districts Map

The voting districts map for the 435-member US House of Representatives changes every decade after reapportionment and redistricting following the Decennial Census.

The overall map remains broadly similar, with districts covering larger land areas in areas of lower population density, and many districts packed into populous metropolitan areas.

Single-district states, those with the smallest populations, are Alaska, Delaware, Vermont, Wyoming, North Dakota, and South Dakota. Montana recently gained a second seat for the 2022 Congress.

Fig. 1 - Map show 435 US congressional districts (2020); states in green have single districts

Manipulating Voting Districts

Now comes the fun part! The process of manipulating voting districts is a high-stakes game of sorts. The two main sides in the US, Republicans and Democrats, are constantly on guard against their rivals gaining undue influence. Let's see how this works.

Simple Polygons Don't Work

If you look at an electoral district map, you will observe very few squares or other simple shapes (other than Wyoming). This isn't inherent bias. It just means people cluster in urban areas but are spread thinly over the countryside.

You thus have to stretch the district shapes to divvy out people correctly. And that is where the real challenge begins.

Gerrymandering: Packing and Cracking

Understand that the very nature of how populations cluster means voting districts are going to have some odd shapes. A new map proposal might be rejected because it looks like there was intent to do something illegal with the boundaries, but not all lawsuits over this are successful since sometimes geography itself is at fault.

What are people so worried about? Gerrymandering.

Fig. 2 - 1812 Massachusetts cartoon showing the original "Gerry-mander"

The gerrymander was a cartoon salamander (as in mythical, fire-breathing monster) from early 1800s Massachusetts published in a newspaper as a commentary on the way a certain congressional district had been drawn. It looked very suspicious, as if the odd salamander shape of the district had been drawn around areas where a certain type of voter resided, simultaneously excluding other types of voters. Elbridge Gerry was the governor at the time and was seen to be behind the ploy. Voila! Gerrymandering was born.

Packing Voters into Districts

Ideally, you want your party to win every seat in the state. In most cases, that's not possible, particularly in "swing" states with evenly matched numbers of Republican and Democrat voters.

Every seat counts, meaning every electoral district counts, meaning where every voter lives in a district counts. What if you could draw the lines in such a way that most people who are almost certain to vote for the opposing party are "packed" into a single district, even if they are spread out over a large area? As long as you can get the district to physically connect as a single polygon (no multiple-polygon districts are allowed in the US), this is feasible.

By packing voters into some districts, their influence in OTHER districts is diluted!

If the geography and math work, you might be able to get away with it.

Cracking Voters across Districts

Packing often goes with cracking. You do both to attempt to get an advantage in the next election (if you don't get overruled by a court).

Let's say you have a solid 80-20 majority in a district. The opposing party wants to win the district, so they need to crack the district by drawing the new lines in such a way that 35 to 40% of the voters end up in neighbouring districts. The redrawn district becomes 40-60 while surrounding districts, say three, add percentages of the cracked voters, but not enough to upset the balance of power. The successful party thus goes from three seats to four seats, while the other party goes from one seat to no seats.

Racial Discrimination

You can't stop all this from happening, but you can halt minority voter disenfranchisement. Courts often block redistricting plans for this reason. They then mandate new districts that, ironically, also may take on gerrymandered shapes.

Voting Districts Examples

One of the best voting districts examples is Illinois's Fourth Congressional District, known as the "earmuffs" for its strange shape. Gerrymandered? You betcha! How did they get away with it? Well, in this case, the federal government ordered it?!

You read correctly. This suburban Chicago district was created on a federal judge order to address Hispanic disenfranchisement. The result is solidly Hispanic and one of the most gerrymandered districts in the country. Hispanic voters from two parts of the city were packed into a single, extremely odd-looking polygon.

Who Does This Stuff???

As mentioned above, states have several ways of determining who gets to redraw the voting districts.

Fig. 3 - Map shows number of US congressional seats per state and who had control of the redistricting process after the 2020 Census. Red: Republican control; Blue: Democrat control; Yellow: bipartisan; Green: independent commission; Gray: No redistricting

This makes all the difference. Only eight states have bipartisan redistricting committees; eight more have independent commissions. The rest are controlled by either Republicans (19) or Democrats (9). As you might guess, they tend to look for partisan advantage.

We'll just leave this quote here: it pretty much sums up the geographical and demographic shenanigans we've described above. It's from the late Thomas Hofeller, a master gerrymanderer: