Wednesday, June 12, 2013

Tract by Tract, Brooklyn Still Isn't Park Slope.

My last post looked at demographic changes in Brooklyn at the Community District level.  My claim was that, despite a lot of conventional wisdom (and Style section stories), only a few areas of Brooklyn have gotten demonstrably "whiter, better educated, and higher earning" over the past decade.

However, some of the statistics were for approximations called "PUMAs" rather than for the districts themselves.  These are basically the "official" approximations, but I thought I would look at the Census tract level to make sure there weren't any discrepancies.  

Unfortunately, only five year estimates are currently available for Census tracts, presumably because of the smaller sample sizes, compared to the three year estimates available for the PUMAs.

The statistics I'd like to check are median household income (MHI) and the percent of residents over 25 with at least a bachelor's degree.  Income support and non-Hispanic white percentage were, I think, both calculated for the current Community District boundaries.

Where did Brooklyn's earnings increase?  Mostly, in a few areas clustered around Park Slope and Williamsburg, Census tracts suggest:

To make sure, let's make a map of the changes, at least where we can.  The Census bureau has relationship files and I removed all polygons with no 2010 population, along with polygons from all 2000 or 2010 tracts that didn't have an income estimate (both colored white below).

Some tracts were still merged, split, or otherwise altered between 2000 and 2010 (those are colored yellow below).  But about 90% of Brooklyn lives in the remaining tracts.

(The precise map you get depends on if you use Summary File 3 or Summary File 4.  The former has a few more tracts with an estimated MHI.  If you use SF3, then there are a few more "incomparable" areas.  Since these tracts didn't have too many people in them, I couldn't decide which made more sense, so I thought I'd include both versions.)

Once again, the Williamsburg and Park Slope areas saw significant increases, and so did some nearby neighborhoods, like a few tracts in Bushwick right next to Williamsburg.

But otherwise, most of Brooklyn's Census tracts had stagnant or decreasing median household incomes (or at least incomes with nominal increase below, or barely above, an estimate of the rate of inflation).

In what will come as a surprise to absolutely no one, the greatest single increase (where I could make a comparison) was in DUMBO's Census tract.  The population tripled, and the median income soared from an already high $99,000 to a ridiculous $168,000.

Where did Brooklyn become better educated?  Recall this was the most notable change across the borough: the percentage of Brooklynites over 25 with at least a bachelor's degree had increased by 8 points from 2000 to 2010 (rather, to the 2007-2011 average).  

Looking by Census tract, we can see, once again, that Williamsburg's character has completely changed, but otherwise, it looks like a relatively stable map, with increases in Downtown Brooklyn, Prospect Heights, and (for some reason) an odd horizontal run in Bed-Stuy.

To make sure, let's make a map of the changes.  This time, I was able to use the Census Bureau's relationship files to combine both sets of tracts into directly comparable "clusters" (once again after removing polygons with no 2010 population).

Here's what the change looked like:
This is probably the best argument that there's been widespread change in Brooklyn.  Over 1,500,000 Brooklynites--about 56% of the borough--live in Census tracts or clusters where the percentage of residents over 25 with at least a bachelor's degree increased by more than 4% (the national change).

Where was the greatest increase?  Tract 203, in Prospect Heights.  Over two-thirds now have at least a bachelor's degree, compared to just 21% in 2000.  The change in median household income wasn't nearly as dramatic, in part because Tract 203 still has a significant low-income population.  It's the only tract in Brooklyn where at least 30% of households report an income under $15,000 and at least 30% of households report an income over $100,000.

(I was briefly worried that there might be more of this kind of discrepancy, but overall, median household income is quite well-correlated with percentage of high-income households, and it's a similar change map.)

Remember, the increase doesn't necessarily come entirely from well-educated new residents driving out less-educated old residents.  Some of it could come from old residents picking up degrees, or whatever it is that drove the national increase.

Finally: Yes, these are estimates.  It's possible that there are recent changes the ACS misses, or that response rates are off, and so on.  (Although the suspicion, as I said, seems to be that the Census is missing Hispanic and immigrant Brooklynites.)  But this approach picks up the areas that everyone agrees have gotten much more upscale, and I don't know what evidence there is that it's missing similar changes elsewhere.

Next up?  I realized that it's not too much harder to make these tract-level comparison maps for the whole city, so I'll be taking a similar look at all of NYC.

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