The Redrawn House 被重画的众议院

Congressional districts in the United States are redrawn once every ten years, after the decennial census. That cadence is the rule the country has run on for most of its history. In the past nine months five states — Texas, California, Missouri, North Carolina, and Virginia — broke it. Each pushed through a new map mid-decade, and each map has a clear partisan target.

Read the figure left to right. Texas's legislature redrew thirty-eight districts to convert roughly five seats from blue to red. California passed Proposition 50 to suspend the state's independent redistricting commission for one cycle and redrew fifty-two districts to reverse Texas's gain. North Carolina, already carrying one of the most gerrymandered maps in the country since 2023, tightened it further. The narrow strip across the top puts the three states in their national context — the five mid-decade redraws sit inside (and in two cases against) the sage band of states whose redistricting is supposed to be insulated from a single legislature's hand.

The temptation is to score these maps by how strange they look — Polsby–Popper compactness scores, ratio of perimeter to area, the old "if a district resembles a salamander, it's a gerrymander" heuristic. Mathematicians have spent the last decade demonstrating that this heuristic doesn't work. A district can hug a coastline and look ugly while being perfectly fair; another can be a tidy rectangle and be drawn to crack a city in half. The better test, brought before the Supreme Court in Rucho v. Common Cause (2019), is statistical: generate tens of thousands of legal maps by Markov chain Monte Carlo, plot the partisan outcomes, and see whether the proposed map sits at the extreme tail of that distribution. Several of the maps shown here do — at the 99th percentile or beyond. Yet Rucho closed federal courts to partisan-gerrymandering claims. The math is sharp; the legal teeth are gone.

What remains is structural. Single-member, winner-take-all districts are the soil that gerrymandering grows in: a few thousand voters moved across a line can move a seat. Cambridge, Massachusetts; Eastpointe, Michigan; Portland, Oregon — three places that have switched their local elections to ranked-choice voting in multi-member districts — show what a country less hospitable to this kind of map would look like. Until that change reaches the House, the figure above is what the country looks like when both parties decide that the old once-a-decade rule is no longer binding.

A note on the dots. Each dot is one congressional district; colour encodes the partisan lean projected by widely-cited models (Cook PVI / Dave's Redistricting). Dot positions inside each state outline are stylized — they sit roughly inside the state but do not reproduce district shapes. For the actual boundary lines see Census TIGER (linked below). Seat counts and outlier percentiles are best public estimates as of the article's date and will move as litigation resolves; the strip across the top is honest about what's structural (sage tint) and what's an event of the moment (the deep dots).

美国的国会选区是每十年随人口普查重画一次的。这是这个国家大部分时期 运行的节奏。但在过去九个月里——5 个州（得州、加州、密苏里、北卡、 弗吉尼亚）打破了这个节奏。每一州都在中期通过了一张新图，每一张 都有清楚的党派靶子。

这张图从左到右读。得州的州议会重画了 38 个选区，把约 5 个席位 从蓝刻成红。加州通过 Proposition 50，把本州的独立划区委员会 暂停了一个周期，再重画 52 个选区，把得州的"红涨"反过来吃回去。 北卡——自 2023 年起就背着全国最严重 gerrymandering 名声之一—— 又把那张图勒紧了一些。顶部那条窄带把这三州放进全国语境： 5 个中期重画的州，恰好嵌在（其中两个甚至对抗着） sage 染色的那一带——那本来应该是不受单一议会之手控制的州。

诱惑是去用"图丑不丑"来打分这些图——Polsby–Popper 紧凑度、 周长与面积之比、那条老经验"如果一个选区长得像一条蝾螈， 它就是 gerrymander"。数学家们在过去十年里反复证明这条经验 不成立。一个选区可以贴着海岸线、长得很丑，但其实公平；另一个 可以是规整的矩形，却恰好把一座城市切两半。更可靠的检验， 在 2019 年的 Rucho v. Common Cause 案中被带上了 最高法院，是统计学的：用 Markov Chain Monte Carlo 生成数万张 合法选区图，画出每张图的党派结果分布，再看待审的那张图 是否落在分布的极端尾部。本图中的若干新图正是如此——99 百分位 甚至更外。但 Rucho 同时关闭了联邦法院受理党派 gerrymandering 诉讼的大门。数学还在；司法的牙齿没了。

剩下的是结构问题。单议席、胜者全得的选区，是 gerrymandering 生长的土壤：把几千张选票挪过一条线，就能挪走一个席位。 马萨诸塞州 Cambridge、密歇根州 Eastpointe、俄勒冈州 Portland—— 这三个把地方选举换成多议席选区 + 排序复选制的地方——预演了 一个对这类地图不那么友好的国家会是什么样。在这种改变抵达 众议院之前，上面这张图就是当两党都决定"十年一画"那条 老规矩不再有约束力时，这个国家的样子。

关于这些圆点。每个圆点 = 一个国会选区；颜色编码采用 被广泛引用的党派倾向模型（Cook PVI / Dave's Redistricting）。 圆点在州内的位置是程式化的——它们大致落在州的轮廓里，但 并不复刻具体选区的形状；真实边界请见下方注明的 Census TIGER 数据。席位计数与离群百分位是文章发稿时的最新公开估计， 会随诉讼推进而变。顶部窄带尽量诚实区分了结构性的（sage 染色） 与一时性的事件（深色圆点）。