# Redistricting for the US House and the US state legislatures

#### lpetrich

##### Contributor
Brian Olson's site has BDistricting -- "What redistricting is and what it could be." - 2010 Redistricting Results

"Below are district maps for US House and state legislatures that have been optimized for equal population and compactness only. No partisan power plays. No gerrymandering."

With House and state-legislature maps for all 50 states.

"What is a district for? ... Districts break down governance into managable pieces."

"What is a good district? ... Across all districts and all people, the best district map is the one where people have the lowest average distance to the center of their district. ... It's also possible for human drawn districts to actually better represent 'communities of interest' and other fuzzy but real sociological features."

#### lpetrich

##### Contributor
Continuing with Brian Olson's "about" page, he takes on the issue of "Compactness Measures":

• Travel time?
• District perimeter/area
• District convex-hull area / precise area
• Just pick simple boundaries along zip-codes/counties/rivers/etc.
Also concerns like
• Will this break up communities?
• Won't this disenfranchise minorities?
He proposes proportional representation as a solution. I agree with him that it's better than contorted districts.

My implementation is a heuristic based gradient descent solver with simulated annealing jitter. It looks at the boundaries between districts and tries to make things better by flipping one block from district A to district B (and possibly over some number of steps, other blocks from B to C and C to A). It doesn't actually directly optimize the measure of population compactness, but looks at related measures like the ratio of the block's distance to the average edge blocks' distances from each district's center, and the ratio of the populations of the two districts the block might go into. Each district grabs up to one block, then centers are recalculated and the cycle begins again checking all the edge blocks.

#### lpetrich

##### Contributor
RangeVoting.org - Splitline districtings of all 50 states + DC + PR with the splitline algorithm described in RangeVoting.org - Gerrymandering and a cure - shortest splitline algorithm
The algorithm:
2. Let N=A+B where A and B are as nearly equal whole numbers as possible.
(For example, 7=4+3. More precisely, A = ⌈N/2⌉, B=⌊N/2⌋.)
3. Among all possible dividing lines that split the state into two parts with population ratio A:B, choose the shortest. (Notes: since the Earth is round, when we say "line" we more precisely mean "great circle." If there is an exact length-tie for "shortest" then break that tie by using the line closest to North-South orientation, and if it's still a tie, then use the Westernmost of the tied dividing lines. "Length" means distance between the two furthest-apart points on the line, that both lie within the district being split.)
4. We now have two hemi-states, each to contain a specified number (namely A and B) of districts. Handle them recursively via the same splitting procedure.

#### lpetrich

##### Contributor
Auto-Redistrict - the algorithm tries to optimize districts by:
• Geometry
• Equal population
• Contiguous
• Compact
• Minimal county / municipality splits
• Equality
• Competitive
• Proportional
• Minimal partisan gerrymandering (maximal "partisan symmetry")
• Minimal racial gerrymandering (maximal voting power equality)
It uses a genetic algorithm:
1. Initialize. First, the population of potential maps is initialized. It could either start off totally random, or you could use the current electoral district shapes to start it off.
2. Evaluate. Then the fitness of each map is evaluated on each of the criteria (in our case, compactness, equal population, competitiveness, proportional representation, etc.)
3. Select. The best scoring maps are selected for reproduction,
4. Recombine. and randomly recombined to form new maps, that are hybrids of the best maps.
5. Mutate. Finally these maps are "mutated" slightly so that other potential maps that are similar to them are explored.
6. (Repeat). This is the new population of potential maps. The process repeats from step 2.
The page then goes into more detail about the optimization criteria.

I could not find anything on the algorithm's results or how long it takes to run.

#### Tigers!

##### Veteran Member
Had a thought on a simple fix for gerrymandering:

Every political party with at least one seat submits a proposed map. The map with the lowest total boundary distance wins. Secret "bids".
Or have an independent body produce the map. A body that has no ties to any pollie or party, that stands to gain nothing from an electoral map. the parties/polles are free to critique said body's map but they them selves do not generate a map.
Having pollies generate a map means they will aim to maintain, at the very least, the status quo, thus guaranteeing gerrymandering will continue.

#### Loren Pechtel

##### Super Moderator
Staff member
uses a genetic algorithm:
1. Initialize. First, the population of potential maps is initialized. It could either start off totally random, or you could use the current electoral district shapes to start it off.
2. Evaluate. Then the fitness of each map is evaluated on each of the criteria (in our case, compactness, equal population, competitiveness, proportional representation, etc.)
3. Select. The best scoring maps are selected for reproduction,
4. Recombine. and randomly recombined to form new maps, that are hybrids of the best maps.
5. Mutate. Finally these maps are "mutated" slightly so that other potential maps that are similar to them are explored.
6. (Repeat). This is the new population of potential maps. The process repeats from step 2.
The page then goes into more detail about the optimization criteria.

I could not find anything on the algorithm's results or how long it takes to run.

Genetic algorithms aren't a good thing here--they are not reproducable so there's no way to figure out if somebody tampered with the results a bit. Redistricting should be done by a reproducible means.

#### Loren Pechtel

##### Super Moderator
Staff member
Had a thought on a simple fix for gerrymandering:

Every political party with at least one seat submits a proposed map. The map with the lowest total boundary distance wins. Secret "bids".
Or have an independent body produce the map. A body that has no ties to any pollie or party, that stands to gain nothing from an electoral map. the parties/polles are free to critique said body's map but they them selves do not generate a map.
Having pollies generate a map means they will aim to maintain, at the very least, the status quo, thus guaranteeing gerrymandering will continue.

But how do you ensure they are actually independent?

#### lpetrich

##### Contributor
Genetic algorithms aren't a good thing here--they are not reproducable so there's no way to figure out if somebody tampered with the results a bit. Redistricting should be done by a reproducible means.
That's a problem with stochastic algorithms in general, like simulated annealing. A deterministic alternative is gradient descent, with avoiding the most recently-used change directions: "tabu search". Another deterministic alternative is K-means clustering, though it cannot optimize features like district perimeters. All these algorithms need initial conditions, and those are usually calculated randomly.

Brian Olson gets around the randomness part by doing repeated runs with different random-number values, and one can also do so by specifying the random-number algorithm and the seeding.

#### lpetrich

##### Contributor
One may want to use some programming language's standard-library function for random numbers, but that has a problem. It may not be very well-documented. If one uses an open-source implementation like GCC or NumPy, one may be able to find the algorithm if one burrows through the source code in some archive somewhere. But that's not very feasible with a proprietary implementation.

In fairness, C++11 introduced some well-documented random-number generators in its standard library.

This is much more of a problem with random numbers than it is for (say) square root, log, exp, or trig functions, because different algorithms produce very different sequences of numbers.

Back to redistricting.

Alabama now has a map. Its 7 districts are one strongly Democratic one that includes the state's biggest cities, Birmingham and Montgomery, and 6 strongly Republican ones for the rest of the state.

538 is confused about North Carolina. Does it have a map? Or is its new map still in the final stages of legislative approval?

Michigan: Dec. 31, 2021 - Date by which commission says it will enact a map - now at 3 maps, named "Apple", "Birch", "Chestnut". What next? Let's see ... "Dogwood", "Elm", "Fir", "Ginkgo", "Hickory", "Ivy", "Juniper", "Kapok", "Larch", "Maple", "Nut", "Oak", "Pine", "Quercus", "Redwood", "Spruce", "Tamarack", U? V? W? X? "Yew" Z?

New Hampshire: Nov. 18, 2021 - Deadline for House Special Committee on Redistricting to propose draft of congressional map - Democrats want both districts to be neck-and-neck, while Republicans want one Democratic-leaning district and one Republican-leaning district.

Ohio: Nov. 30, 2021 - Deadline for legislature to pass temporary map if commission doesn't succeed - a third map, from State Senate Republicans, even more gerrymandered than the State House Republicans' map.

#### Tigers!

##### Veteran Member
Had a thought on a simple fix for gerrymandering:

Every political party with at least one seat submits a proposed map. The map with the lowest total boundary distance wins. Secret "bids".
Or have an independent body produce the map. A body that has no ties to any pollie or party, that stands to gain nothing from an electoral map. the parties/polles are free to critique said body's map but they them selves do not generate a map.
Having pollies generate a map means they will aim to maintain, at the very least, the status quo, thus guaranteeing gerrymandering will continue.

But how do you ensure they are actually independent?
Fortunately in Australia our Electoral Commissions, both State and Commonwealth, have been in existence since just after WW1. They have a near perfect record of impartiality and competence. I say near perfect as this century we have had a few examples of carelessness in handling ballots, necessitating new elections or rather part elections.
The way you Yanks divide yourself into opposing factions so quickly would make it difficult but you have to start somewhere.
As a start the body is answerable only to the parliament or legislative body that formed it, not the government of the day. No existing, former or wanna-be politicians can be members. No members can belong to a political party or have worked for a political party or candidate, paid or unpaid.
In the state of Victoria where I live you cannot work for the Electoral Commission if you have represented or worked for a political party or candidate within the last 5 years or 2 electoral cycles, whichever is longer. You cannot even hand out pamphlets or flyers for a party or candidate. You cannot put a political sign on your property including a vehicle as your impartiality will be called into question. Paid or volunteer work does not matter. Similar rules apply for the Commonwealth Electoral Commission.
Members are paid by the parliament, not the parties or others. They are considered to be public servants and follow the public servant rules.
They produce the maps and then put them up for public discussion for a time. These maps are based upon population only. The maps merely show the boundaries of the electorates, not where the polling stations etc. will be. That is a separate process. All interested parties including political parties, candidates, individuals etc. can lodge a request or protest to amend an electorate based solely upon population. Any changes are made based solely upon population and are made by the commission. Naturally the perceived independence of the commission is important.

There are 2 important features
1. The body is independent of the parties, candidates, government of the day etc. Responsible only to the parliament that created it.
2. Boundaries are based solely upon population. If another criteria is allowed esp. past voting patterns then gerrymandering will occur.

#### lpetrich

##### Contributor
Thanx, Tigers! Nice to know what goes on elsewhere in the world.

Back to US redistricting.

I wasn't sure about North Carolina earlier, but I am now. That state now has a map. Iowa also does so, that half-competitive half-Republican one.

Wisconsin's "People's Maps Commission" has come out with a map. It makes one of the Republican-leaning districts competitive, unlike the Republican legislators, who proposed a R 6 D 2 map, much like the current one. The state gov't is divided between a Democratic governor and a gerrymandered-Republican legislature, so expect the map to go to the courts.

#### Loren Pechtel

##### Super Moderator
Staff member
The way you Yanks divide yourself into opposing factions so quickly would make it difficult but you have to start somewhere.
As a start the body is answerable only to the parliament or legislative body that formed it, not the government of the day. No existing, former or wanna-be politicians can be members. No members can belong to a political party or have worked for a political party or candidate, paid or unpaid.
The legislative body created it, they can pick people that will support their position.

Perhaps yours is honest but this isn't proof of it.

#### lpetrich

##### Contributor
Nevada has a proposed map, going from +22 -1 -5 -16 to +5 +4 +2 -13

This is to support Democratic incumbents in that state, by giving them some Democratic voters in the Las Vegas area. The existing map has a strongly-Democratic district for Las Vegas proper, and some barely-Republican districts for the city's suburbs. The new map splits up Las Vegas to give its voters to more districts.

Gerrymandering? Yes, and it shows a risk that that activity can have. If one wants to expand one's reach, one may distribute one's most committed voters among more districts, but doing so gives all of them weaker majorities. If Nevada became a little bit more Republican, then all three Democrats could be replaced by Republicans, while with the existing map, one Democrat would be somewhat safe.

#### lpetrich

##### Contributor
Florida now has four proposed maps. These maps are not as gerrymandered as aggressively as one might expect, likely because of wanting to protect Republican incumbents. Much like in Texas.

California now has a proposed map. It puts Katie Porter into a R+2 district.

#### lpetrich

##### Contributor
California: Nov. 15, 2021 - Deadline for commission to propose draft of congressional map

Florida: June 13, 2022 - Date that candidates begin filing for congressional runs (therefore map should be set by this date)

Nevada: March 7, 2022 - Date that candidates begin filing for congressional runs (therefore map should be set by this date)

Wisconsin: April 15, 2022 - Date that candidates begin filing for congressional runs (therefore map should be set by this date)

Katie Porter's district is now CA-45, at D+6. It will become CA-44 at R+2.

She won by 4.8% in 2018 and 7.0% in 2020. So it'll be a tough race for her.

#### lpetrich

##### Contributor
Montana, Idaho, and Utah now have maps. No surprise for either MT or ID, but all four of UT's districts are heavily Republican, with Salt Lake City being split up between all of them.

How Republicans Have an Edge in the Emerging 2022 Congressional Maps - The New York Times
“Fear is driving all of this,” David Pepper, a former Ohio Democratic Party chairman, said on Wednesday at a hearing to discuss a proposed map that would give Republicans 13 of the state’s 15 congressional seats. “Fear of what would happen if we actually had a real democracy.”

...
Several other states have completed maps for the 2020s that entrench existing Republican advantages. Republicans in Alabama and Indiana shored up G.O.P.-held congressional districts while packing their state’s pockets of Democrats into uncompetitive enclaves. In Utah, a new map eliminates a competitive district in Salt Lake City that Democrats won in 2018. Republicans have made an Oklahoma City seat much safer, while Colorado’s independent redistricting commission shored up the district of Representative Lauren Boebert, a Republican and Trump ally, so much that her leading Democratic opponent, who had raised $1.9 million, dropped out of the contest to defeat her. And in Texas, Gov. Greg Abbott signed into law a map that protects the state’s 23 Republican incumbents while adding two safely red seats, a year after the party spent$22 million to protect vulnerable House members.

...
In one of the few states where Democrats are on offense, Illinois will eliminate two Republican seats from its delegation and add one Democratic one when Gov. J.B. Pritzker signs the map that the state’s Democratic-controlled Legislature approved last month. New York is likely to add seats to the Democratic column once the party’s lawmakers complete maps next year, and Maryland Democrats may draw their state’s lone Republican congressman out of a district.

Democrats in Nebraska also managed to preserve a competitive district that includes Omaha after initial Republican proposals sought to split the city in two.

...
Wisconsin Republicans on Thursday passed a congressional map that would shift a Democratic seat to certain Republican control, though Gov. Tony Evers, a Democrat, promised to veto it. Michigan and Virginia, which had gerrymandered districts, have adopted outside commissions to draw new lines. Pennsylvania has a Democratic governor certain to veto Republican maps.

And it’s not clear what California’s independent commission will do when it completes the state’s process later this year.

...
Still, Republicans have far more opportunities to press their advantage. G.O.P. lawmakers in New Hampshire proposed changing a congressional map largely unaltered since the 1800s to create a Republican seat. In Georgia, Republicans are set to place Representatives Lucy McBath and Carolyn Bourdeaux, Democrats who hold seats in Atlanta’s booming northern suburbs, into a single Democratic district while forming a new Republican seat.

Officials in both parties are preparing for years of legal fights over the maps, with the potential for courts to order the redrawing of maps well into the decade. Lawsuits have already been filed over maps in Oregon, Alabama, North Carolina and Texas.

#### lpetrich

##### Contributor
Nevada now has a map: +5, +4, +2, -13

California: Dec. 27, 2021 - Deadline for commission to enact congressional map

Maryland: Feb. 22, 2022 - Deadline for congressional candidates to file (therefore map should be set by this date) - the legislature has now proposed 4 maps, with the eastern district (MD-01) ranging from strong Republican to competitive. All the other districts are Democratic.

Michigan: Dec. 31, 2021 - Date by which commission says it will enact a map - still at those three tree maps.

Virginia: Nov. 23, 2021 - Deadline for commission to submit new map to legislature if initial map is rejected - Nov. 30, 2021 - Deadline for legislature to approve or reject new map if initial map is rejected - because of a missed deadline, the state's Supreme Court is now supervising redistricting.

Washington: April 30, 2022 - Deadline for state Supreme Court to enact map if commission doesn't succeed - that body is now in charge of redistricting there also, also because of a missed deadline.

#### Jimmy Higgins

##### Contributor
It appears my claims that the GOP gerrymandered themselves into a corner were wrong, as they have turned Ohio into fucking Utah! The two Democrat districts... +55 and +40. WTF?! +55 means 77 to 22. My district is one of the only purples, with a +4 R. Medina verses Summit County.

And we have a bipartisan redistricting board... which didn't come up with a map, because the GOP can just delay delay delay and come up with this monstrosity.

#### Tigers!

##### Veteran Member
Massachusetts, Ohio, and Oklahoma now have maps.

Maps of Alabama, North Carolina, Oregon, and Texas are now being litigated over, and the courts will likely decide the maps of Virginia, Washington, and Wisconsin.

What Redistricting Looks Like In Every State | FiveThirtyEight
The cynic in me says "Why bother going to courts about the districts? Let the judges decide the result of the elections. Cut out all those middle persons and save a lot of time & effort"

Truly you septics are stuffed.

#### lpetrich

##### Contributor
Illinois now has a map. The map that its legislature agreed on.

Georgia: March 7, 2022 - Date that candidates begin filing for congressional runs (therefore map should be set by this date)

Minnesota: Feb. 15, 2022 - Deadline for final congressional map - its State House is Democrat-dominated and its State Senate is Republican-dominated, and if they cannot agree, then the courts will come in for yet another map.

Tennessee: April 7, 2022 - Deadline for congressional candidates to file (therefore map should be set by this date)

Over in Maryland,

Mckayla Wilkes for Congress on Twitter: "Steny Hoyer, a man who has been in Congress since 1981, is insisting that his personal preferences determine Maryland's district lines until 2032. Even though federal reps aren't supposed to even be involved in the process at all.

She's hoping to primary him. He's in MD-05.

Noting
Breaking: Maryland Dem legislators are preparing to advance a modified version of this 7D-0R-1C draft (instead of a pure 8D-0R map) that would leave Freedom Caucus Rep. Andy Harris (R) with a path to victory by excluding blue Annapolis from #MD01. Actual draft coming soon.

National Dems have been counting on Dem gerrymanders in MD, IL and NY to offset aggressive GOP gerrymanders in GA, NC, OH, and TX among others. But in at least MD, they may not end up w/ anything more than what they already have.

Btw, there seems to be a prevailing thought on here that it's #MD05 Rep. Steny Hoyer (D) holding back Dems from pursuing a more aggressive map, which isn't the case at all. Dems' obstacle is (at least) one incumbent from the Baltimore area.

#### lpetrich

##### Contributor
Of the states, 6 have only one House district, 18 now have new district maps, 16 have proposed maps, and 10 have no maps.

About Maryland, they are now down to two maps, one of the earlier ones with two R seats, and one of the more recent ones with one R seat, though it is R+8 instead of R+28. The state's district boundaries, old and new, look contorted.

#### lpetrich

##### Contributor
South Carolina: March 16, 2022 - Date that candidates begin filing for congressional runs (therefore map should be set by this date)

That state now has a proposed map. It adds some areas to Nancy Mace's district, SC-01, to make it more pro-Republican. Yet more incumbent protection.