Part of the reason the Republicans have control over the House of Representatives is that they have drawn district lines in many states which favor them over Democrats. Also, in Democratic states, you often see Democrats being conservative about the redistricting process, while Republicans tend to be very aggressive. The Democrats prefer to draw districts which keep all of their incumbents very safe, but as a result, they are sending more Republicans to Congress than they could. But Repulicans draw their lines to where they are somewhat less safe than Democrats, but as a result, they send more Republicans to Congress.
Follow below the fold as we examine some redistricting tricks...
Solid Democratic states like New Jersey and Illinois only have 1 seat Democratic majorities in their congressional delegations (7-6 and 10-9 respectively). After the 2000 census, the Republicans had control of the legislatures and governor's offices in Michigan, Pennsylvania, Ohio, and Florida. They aggressively gerrymandered their lines so that they would send far more Republicans to Congress than they ought to. Michigan and Pennsylvania both voted Democratic in 2000 and 2004, so you'd expect them to have majority Democratic delegations. Wrong. Republicans lead 9-6 in Michigan and 12-7 in Pennsylvania. Ohio was close last time...so the delegation should be close, right? Nope, Republicans lead 12-6. How about Florida? It was basically tied in the presidential race in 2000 and had an extremely close Senate contest in 2004. The delegation there should be split right down the middle. Wrong again, Republicans lead 18-7.
To sum it up:
State: 2004 GOP Presidential Vote: %GOP in Delegation:
Pennsylvania 49% 63%
Michigan 48% 60%
Ohio 51% 67%
Florida 52% 72%
Now for the tricks...
To see this gerrymandering in effect, let's create a simplified example: we have a state with 3 million people (we'll assume everybody votes for simplicity's sake) and 6 congressional districts, with half a million people per district. 1 million people live in urban areas, 1 million live in suburban areas, and 1 million live in rural areas. The urban areas favor the Democrats 85%-15%, the suburban areas are split 50%-50%, and the rural areas favor Republicans 70%-30%. This sample state would vote 55%-45% in favor of Democrats.
This state would be reliably Democratic in presidential elections and probably send two Democrats to the U.S. Senate. But let's say that they elect a Republican governor right before redistricting and the Republicans happen to control the legislature. They then pack the urban areas into two overwhelmingly Democratic districts and then split the rural and suburban areas into the four remaining districts. The result:
District 1: Democratic 85%, Republican 15%
Urban: 500,000
District 2: Democratic 85%, Republican 15%
Urban: 500,000
District 3: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
District 4: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
District 5: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
District 6: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
Despite the Republicans being a distinct minority statewide, they will win two-thirds of the seats in Congress in the next election. And with a 60-40 advantage, they will never lose their seats, no matter how strong a challenger you run or how much money you can spend. This state would likely have liberal U.S. senators, but ultra-conservative congressmen, except from the 2 urban districts.
Now typically, when you have the Democrats get into control, they seem to like striking sweetheart deals to avoid confrontation, like in California. So let's say the next time the Democrats have the governor's office and the legislature. The Republicans threaten to sue if the Democrats decide to screw them in redistricting, so let's say they decide that they should just draw the lines so the delegation is 50-50 and everybody is happy. So, you'd get something like this:
District 1: Democratic 85%, Republican 15%
Urban: 500,000
District 2: Democratic 67%, Republican 33%
Urban: 300,000
Suburban: 100,000
Rural: 100,000
District 3: Democratic 58%, Republican 42%
Urban: 200,000
Suburban: 150,000
Rural: 150,000
District 4: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
District 5: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
District 6: Republican 60%, Democratic 40%
Suburban: 250,000
Rural: 250,000
Everybody is safe. But Democrats are still underrepresented because they have 50% of the delegation, though their natural vote share is 55%. So let's say they decide to be a bit more aggressive. They pack all the rural areas into two districts and split up the urban and suburban areas equally into the four remaining districts. The result:
District 1: Republican 70%, Democratic 30%
Rural: 500,000
District 2: Republican 70%, Democratic 30%
Rural: 500,000
District 3: Democratic 67.5%, Republican 32.5%
Urban: 250,000
Suburban: 250,000
District 4: Democratic 67.5%, Republican 32.5%
Urban: 250,000
Suburban: 250,000
District 5: Democratic 67.5%, Republican 32.5%
Urban: 250,000
Suburban: 250,000
District 6: Democratic 67.5%, Republican 32.5%
Urban: 250,000
Suburban: 250,000
Now that's a little more like it. Now the Democrats have a two-thirds majority. All of the incumbents are as safe as can be and the map represents the strength of Democrats in the state. But is this really the best we could do? If we're going to gerrymander a House majority, we'll have to be more creative than that. Aha! Why not split up one of those rural districts and pack it in with some urban and suburban areas. The result:
District 1: Republican 70%, Democratic 30%
Rural: 500,000
District 2: Democratic 55.4%, Republican 44.6%
Urban: 220,000
Suburban: 30,000
Rural: 250,000
District 3: Democratic 55.4%, Republican 44.6%
Urban: 220,000
Suburban: 30,000
Rural: 250,000
District 4: Democratic 63.2%, Republican 36.8%
Urban: 160,000
Suburban: 340,000
District 5: Democratic 64%, Republican 36%
Urban: 200,000
Suburban: 300,000
District 6: Democratic 64%, Republican 36%
Urban: 200,000
Suburban: 300,000
Now that's what we want! A map that grossly overrepresents the Democrats in this state and makes the Republicans go insane. Now we have a 5-1 Democratic majority, representing 83.3% of the districts in the state. The Democrats have 3 60+ districts where losing would be inconceivable. The other 2 districts are solid enough to where they can be counted on to go Democratic. The only way they would be in jeopardy is under the most dire national circumstances for the party. And even then, once things were back to normal, no Republican could hold the seat. Now individual incumbents would much prefer having a 60+ district since it's easier on them, even though it's better for the party if they have slightly less safe, but still solid districts.
If possible, Democrats need to split up Republican (usually rural) areas to dillute their vote and when they need to draw a Republican district, pack as many Republicans in as is possible. The Democratic districts should be safe when possible, but not ridiculously safe. We should do our best to minimize 70-90% districts. For example, if we want a majority African American district, it makes much more sense to make it 65% (which is very stable) than 90%, which dilutes voting power. The Supreme Court has said that partisan gerrymandering is A-OK, so if Republicans are going to be doing it, we should too, or at least make sure the districts are representative of the state, unlike the current lines in Pennsylvania, Michigan, Ohio, and Florida. In these states, Republicans have drawn lines like I suggested in the first example, which grossly overrepresent their numbers in the electorate. At the very least, we should push for fair lines, like in the second example, but preferrably for lines favoring us, like in the third example. But when possible, we need to absolutely screw the Republicans in redistricting, like in the fourth example.