It's become common to speak of "red" and "blue" states, and to note that the "blue" (Democratic) states are richer than the "red" ones. But the states are of widely different sizes, and some are very large, so they are probably not the best units to look at. Representative Marcy Kaptur's office has produced a chart that shows median household income and party control by Congressional district. There is a clear tendency for Democratic districts to have higher incomes--e. g., Ruy Teixeira says "The first page is heavily dominated by blue but the second, poorer page is a sea of red." However, on looking at the chart, it seemed that it wasn't a simple matter of "the richer the district, the more likely to elect a Democrat." Specifically, it seemed that the probability of electing a Democrat first declined and then increased as you went from low to high income. But it's easy to imagine patterns when there's really nothing but random variation, so I looked more systematically. After ranking the districts from low to high income, I computed a 50-seat moving average--seats 1-50, then seats 2-51, 3-52, ....392-441.* The proportion of Democrats against the income of the middle district in the group:
The pattern is even more complicated than I thought--the chance of electing a Democrat first falls, then rises, then remains steady once the median income reaches about $80,000 (about a quarter of districts are above that level). There are hints that it increases again at the very top (9 of the 10 districts with the highest median income are represented by Democrats), but it's not possible to be sure. The Democratic share is at a minimum when the median income is about $65,000.
I don't have any explanation--I'm just offering it as something to think about. A few other observations:
1. The discussion of this chart has treated it as an example of the Democrats' problems with working-class voters, but the individual and district level relationships are different issues. Congressional districts are large (about 800,000 people), so they all contain a range of classes. Consequently, it would be possible for the Democrats to do better in richer districts and better among working-class voters--in fact, this is what a classical Marxist analysis would predict. Of course, this is not the case in the United States today, but it means that the district-level relationship needs its own explanation.
2. Back in the 1950s, Seymour Martin Lipset observed that conservative parties sometimes did better in the poor regions of a nation (e. g., southern Italy). His explanation was that those regions hadn't moved fully into a capitalist economy, so that their voters followed the lead of traditional elites, but this isn't applicable to the US today. Curiously, the issue hasn't received much attention in subsequent research--I don't recall having seen anything, and my searches in Google Scholar drew a blank.
3. A common method for detecting non-linearity is to include a squared term in addition to the original. But when you do that with these data, the t-ratio for the squared term was less than one. In fact, you had to go up to the fifth power before one was statistically significant, and people rarely go that high. So in this case, if you used a polynomial regression, you'd probably miss the non-linearity.
*The chart includes non-voting delegates as well as representatives.
You're right to step down a level from state to district, but do income comparisons mean anything on a national level, even broken down at the district level? After all, an 80yr old 3-bedroom suburban home near Seattle could sell for $1M, while the same home in Bangor PA would sell for $200K. Salaries, in turn, reflect the local cost of living.
ReplyDeleteWhat you need for this kind of comparison is a local economy adjustment, something analogous to The Economists' "big mac" index. Work out the annual median cost of housing per sq foot and adjust the income by the square footage it buys.
Also there are problems with this even at the congressional district level, since as I'm sure your well aware congressional districts are rigged to "hide" opposition voters. So one district that I know of incorporates very wealthy tech subdivisions near a major city and parts of several very poor counties over 200 miles away. Probably state house districts would be better - TX, for example, has 38 congressional seats but 150 state house seats.
I'm curious how things like stock awards play into "income". I'm aware they aren't "income" in a tax sense. But they are clearly "income" in the sense of how people spend. And tech companies provide a lot of compensation through stock options, so if you're looking for "income" in the sense of what people spend, you'd really need to include stock compensation. It's a small proportion of the national population, but it's a critical part of the cost of living in some of the highest cost areas.
Last but not least obviously retired people - a growing portion of the country to say the least! - generally have lower incomes, and if you're not capturing SS or other types of non-work pay, then you're missing a lot of spending potential.