Probably worth pointing out that the great hollowing out of journalism is a likely causal factor here. The chain of events went something like:
1. Web comes out and makes it trivial to distribute information for nearly free.
2. Users find enough "information" (in quotes because I mean "data that satisfies their instinctual desire to feel in the know" regardless of its actual value) on the web for free that they don't want to pay for their local newspaper anymore.
3. Dying paper subscriptions forces newspapers to go online. Even so and even with copious ads, their profit margins collapse.
4. The only news agencies that survive are national news because they can aggregate their journalism costs over a larger number of readers.
5. Bereft of money, local news agencies get bought up by conglomerations that produce "local" news which is a slurry of national stuff, press releases, and relatively low quality local reporting.
6. People stop reading the local stuff entirely since it's frankly just not good any more.
7. Now everyone is only clued in to national politics since national news sources rarely write about state or city politics.