Every ten years, there’s a census. That decennial count is long and tedious and arduous…and important. Because it confirms who lives where so the Federal Government properly allocates resources, so services go to the places that need them most and - yes - so states gain or lose seats in congress and have the opportunity to redraw all their state and Congressional lines.
That means, every 10 years, states start what has famously been one of the most partisan and divisive processes in politics. Because one strategic line can mean the difference in party control in not just the state legislatures but also in congress.
Cheddar explains how gerrymandering works and why it exists.