ABC News’ Rick Klein reports: Despite record levels of displeasure at members of Congress, the outcome of more than two-thirds of House races isn’t in serious doubt this year. The main reason: gerrymandering, or the process by which voting districts are sliced and diced to determine a particular political outcome. With the 2010 Census set to change the number of House members states send to Congress, redistricting is a major stealth issue in races this year. The results of the latest round of redistricting will last a decade, and the process promises to be as politicized as ever. We checked in with Jeff Reichert, the filmmaker behind a new documentary, “Gerrymandering,” on ABC’s “Top Line” today. “Most people are really unaware that this happens. Most folks don't really think about the fact that they live in a district,” Reichert told us. “Somebody chooses who gets to be in the district and who gets to be in other districts. And as we went across the country and asked people from Iowa to DC to California and Texas, 'What do you know about gerrymandering," the most common response was 'Gerry who?' ” Two of the nation’s largest states – California and Florida – are considering major changes to the way they redraw districts. But it’s going to be hard to divorce politics from that most basic political precept – which voters live where. “It's always going to be a little messy, it's always going to be a little sloppy,” Reichert said. Watch the full “Top Line” segment with Jeff Reichert HERE. I also took an in-depth look at the politics of redistricting on ABC’s “World News” last night. Read more about it, and watch that segment, HERE.