The NPR program Fresh Air had an interview with David Daley, who wrote the book Ratf**ked, The True Story Behind the Secret Plan to Steal America's Democracy. I'm sure the book as seen in stores won't have those two asterisks. Dave Davies hosted the program and the transcript is online. The program covered the major points of the book. I'm sure the book goes into great detail.
In 2009 GOP strategist Chris Jankowski realized that the national census was to be done the next year and congressional district maps would be drawn the following year. He created Operation RedMap to use national GOP money to target enough state legislature seats in 2010 to flip control of several states to the GOP. The targeted districts were flooded with mailers precisely calculated to turn voters against the Dem incumbent. Several state houses were successfully flipped, though a general GOP tide that year gave them a big margin of safety.
Once in power and the census data available GOP operatives went behind closed doors and demanded secrecy. They used the program Maptitude, which has all that census data loaded and allowed them to finely craft districts for their advantage. In Pennsylvania in 2012 Obama won the state by 310K votes. There were 100K more votes for Dem House candidates than for GOP. Yet the congressional seats were awarded 13-5 for the GOP. Yes, 51% of the vote becomes 28% of the seats.
Of course, there has been gerrymandering in the past. But the Maptitude program didn't exist until the 2011 redistricting season and it allows the maps to be more finely gerrymandered than could be done before.
This will be difficult to undo. State legislatures were also highly gerrymandered. That means they are rigged to elect GOP legislators in 2020 when the maps are drawn again, even if there is a big DEM wave to re-elect a Dem president. Undoing this will take a state-by-state effort to take redistricting out of the hands of the legislature. When that has come up for a vote it wins. But that takes time (significant education effort will be needed before it is tried in Michigan).
Here is where we grumble at the Dems. In individual races the GOP sprung the trap so late in the campaign the Dem candidate didn't have time to respond. But in March of 2010 Karl Rove wrote an op-ed piece in the *Wall Street Journal* announcing the GOP's intentions. And the Dems … did nothing. Daley describes it as "political malpractice." And we will live with it for decades.
The interview mentions Michigan district 14. This is what that district looks like. There is a strong horizontal line in the image. Below it is Detroit. Above it is suburbs. The node at the top is Pontiac.