What is the difference between cracking and packing

Luckily, packing and cracking creates a distinctive pattern of wins for both the perpetrator and the victim parties, wherein the victim party wins its few seats by overwhelming margins and the perpetrating party wins its many seats by considerably lower margins. This pattern, and thus partisan gerrymanders, can be detected with the help of a little math. The two-sample t-test, perhaps the most widely used statistical test of all time , tests how similar two groups of numbers are.

In the case of gerrymandering, the t-test can determine how similar the winning vote shares are for the districts won by Democrats to those for districts won by Republicans. In a perfectly fair world, it could be assumed that these two groups of vote shares would be very similar. Each party might expect to see wins in a mix of strongly partisan districts, moderately reliable districts, and tossups—but each party should expect to have a roughly similar mix. In a gerrymandered state, by contrast, the victim party mostly has strong wins in their packed districts and the perpetrating party mostly has small but safe wins.

The t-test can check for this distinctive pattern of lopsided outcomes, and can check for the probability that such a pattern might have arisen by chance. If an outcome was unlikely to have occurred by chance alone, that may indicate that the state suffered a partisan gerrymander.

Votes for other candidates, which were small in number, are not shown. The Assembly district boundaries are displayed in a white outline. Zooming in on Milwaukee, several Assembly districts that overlap with the the city have extremely high concentrations of Democratic voters, especially in districts 8 , 10 , 11 , 16 , 17 , 18 and These parts of Milwaukee also display a dramatic concentration of lower-income African American residents, who are much more likely to vote for Democrats. In fact, Milwaukee has arguably the strongest patterns of segregation by race and class of any city in the nation.

A map of the state legislative districts approved in through a bipartisan process similarly shows several central Milwaukee districts with very high concentrations of Democratic voters.

Evidence of cracking is a bit more obvious upon examination of the map for the Milwaukee region. A close look at the suburbs shows a ring of districts which each have a little piece of the city of Milwaukee, rich in Democratic voters, and a large piece of the surrounding suburbs, which are strongly Republican-leaning. This ring includes districts 13 , 14 , 15 , 20 , 22 , 23 , 24 , 82 , 83 , and 84 — all but one of these 10 seats was held by a Republican in How different is the map from the previous set of legislative districts?

The map reveals a radically different political geography in the Milwaukee suburbs. The most notable difference is that in , districts were by and large drawn to respect the Milwaukee County boundary, the vertical line that runs down most of the center of this map view.

The creators of the districts did not follow the Wisconsin Constitution's directive that legislative districts should respect county boundaries whenever possible, and created a map that cracked the central and near-suburb bloc of Democratic voters across many districts that reach into the far-flung and deeply conservative suburbs of neighboring Waukesha, Ozaukee and Washington counties.

These suburbanized areas are populated in large part by affluent, white conservative voters. In the era of white flight, whites left Milwaukee, city and county, in favor of neighboring counties. The historical suburbanization process itself led to counties with very different political profiles.

Given the state constitution's requirement that districts preserve communities of interest, Assembly members who represent constituents across a county boundary are potentially problematic.

One of the unique things about Gill v. Whitford is that, unlike many other gerrymandering cases, the Wisconsin Assembly districts do not have bizarre shapes. The authors of the map were able to preserve relatively compact and even-looking districts.

However, as argued before the U. Supreme Court, evidence of gerrymandering processes like packing and especially cracking are present its districts. The plaintiffs in the case argued that mathematical evidence of cracking and packing shows that the maps are a partisan gerrymander, intended to strengthen Republican control of the state Legislature and disenfranchise Democratic voters.

One metric of cracking and packing discussed during the case was the efficiency gap, a formula which compares individual votes cast to the total partisan representation in government. When the balance of power in state legislature deviates substantially from the balance of votes at the individual level, lots of people are being represented by someone in the opposing party — deemed by this measurement as evidence of a partisan gerrymander.

In November , a three-judge federal court ruled that Wisconsin's state Assembly district map constitutes a partisan gerrymander. The U. District Court for the Western District of Wisconsin found that the map's overall effect is to tip the balance of power toward Republican candidates, helping to ensure the party's control of the upper and lower houses of the state Legislature.

In addition, the demographic patterning of the districts suggests that the map is inconsistent with a basic premise of representative government — to allow communities of interest to be represented by an official they elect. The cracking present in the districts of the Milwaukee suburbs is perhaps the strongest example of this force in action.

Supreme Court is issuing its ruling on the case in June A closer look at the and Wisconsin Assembly districts, along with the presidential election votes, are available in an interactive map created by the UW Applied Population Lab. Skip to main content. Malia Jones. UW Applied Population Lab. Caitlin Bourbeau. On the state level, gerrymandering has also led to significant partisan bias in maps. For example, in , Democrats in Wisconsin won every statewide office and a majority of the statewide vote, but thanks to gerrymandering, won only 36 of the 99 seats in the state assembly.

Regardless of which party is responsible for gerrymandering, it is ultimately the public who loses out. Residential segregation and racially polarized voting patterns, especially in southern states, mean that targeting communities of color can be an effective tool for creating advantages for the party that controls redistricting. This is true regardless of whether it is Democrats or Republicans drawing the maps. Common Cause greenlighting partisan gerrymandering has made things worse.

The Voting Rights Act and the Constitution prohibit racial discrimination in redistricting. But because there often is correlation between party preference and race, Rucho opens the door for Republican-controlled states to defend racially discriminatory maps on grounds that they were permissibly discriminating against Democrats rather than impermissibly discriminating against Black, Latino, or Asian voters.

Targeting the political power of communities of color is also often a key element of partisan gerrymandering. This is especially the case in the South, where white Democrats are a comparatively small part of the electorate and often live, problematically from the standpoint of a gerrymanderer, very close to white Republicans. Even with slicing and dicing, discriminating against white Democrats only moves the political dial so much. Because of residential segregation, it is much easier for map drawers to pack or crack communities of color to achieve maximum political advantage.

Gerrymandering is a political tactic nearly as old as the United States. But gerrymandering has also changed dramatically since the founding: today, intricate computer algorithms and sophisticated data about voters allow map drawers to game redistricting on a massive scale with surgical precision.

Where gerrymanderers once had to pick from a few maps drawn by hand, they now can create and pick from thousands of computer-generated maps. Baker v. Carr : The U. Supreme court ruled that the Tennessee state government needed to allocate seats in their legislature in proportion to their population, setting the precedent for future legislatures and how they apportioned their seats.

Reynolds v. Bush v. Vera : The Supreme Court found that Texas was using race as a predominant factor in redistricting three Hispanic dominant districts, as opposed to political interest. Evenwel v. Supreme Court found that the constitution lets states use their total population to draw legislative districts, as opposed to their total-voting population.

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