My recent Dogs of New York, post got circulated a little. On Friday I got a very nice note from William Kornblum, an urban and community studies sociologist who these days is emeritus at CUNY. In the 1980s, Bill studied the people who use Central Park and wrote a report for the Central Park Conservancy. Some of that work counted dog-walkers.

He reminded me that parks in New York City see a lot of dogs. NYC Parks estimates about 1.5 million canine visits to Central Park each year. That is about 4,100 visits a day, to one park. He also asked:

Is there a size gradient perhaps? Larger dogs out on the periphery where there is more room? Smaller dogs in the dense apartment neighborhoods?

This is a good question; one the data I have can almost answer. The main problem is that the license data contained in nycdogs do not record the size or weight of any particular dog. Licenses do record the breed that the owner reports (though, as we saw before the modal breed reported is “Unknown”). But let’s see how far we can get by leveraging our knowledge of breeds.

To begin we need to give each breed a size. For this I used the American Kennel Club’s breed weights. The AKC lists a weight range for each breed it recognizes, from its breed standards. Tiago Filho collected these into one table for 277 breeds in 2020. I had to make a few adjustments to reconcile it with the breeds recorded in nycdogs, most notably for two popular city breeds. First, the AKC lists one Dachshund range that covers both sizes within this breed. Owners often record “Miniature” in the breed name, so I gave those dogs the AKC miniature limit of 11 pounds. Second, Pit Bulls are among the most common dogs in the city, but to my knowledge the AKC does not register them. I used the United Kennel Club’s American Pit Bull Terrier standard instead.

I assigned each breed a “typical weight”, which is the middle of its range. Some standards give only one figure, such as “not more than 6 pounds” for a Chihuahua. In those cases I used that number. This is not ideal. A breed standard describes a show dog, not the dog you see in the park. (Though, of course, in some NYC parks those might be the same. But not in general.) Real dogs will be heavier or lighter than their standard. Still, a Great Dane is reliably bigger than a Yorkie, and it’s the relative differences we’re interested in.

The second problem is that many dogs have no breed we can use. I work with an approximation of one record per dog, as in the first post, which gives about 358,000 dogs. I can only assign a breed size to about 60 percent of them:

• About 22 percent are crossbreeds, such as “Labrador Retriever Crossbreed”. A mix could be any size. I chose not to guess.
• About 10 percent have no breed recorded, mostly “Unknown”.
• About 6 percent are “designer” breeds, such as the up-and-coming Goldendoodles, Maltipoos, and Morkies. No kennel club sets a standard for these.
• About 1.5 percent are Poodles with no size given. A Toy Poodle and a Standard Poodle differ by about 50 pounds, so again, I chose to drop these.

Now, if the missing dogs were spread evenly across the city, the missingness would not matter all that much. We can try to check that. Here is a map showing the share of dogs in each ZIP code that have a breed size.

Coverage runs from about half to about two-thirds of dogs in each ZIP code. It is highest on the West Side of Manhattan and in parts of eastern Queens. It is lowest in central Brooklyn. So, dogs are not MCAR in the city. The maps and analysis below is restricted to describing dogs with a known breed, and that group is not quite the same in every part of the city.

Where the big dogs are

For each ZIP code with at least 50 dogs of known size, I calculated the median typical weight. (As before, I use the city’s MODZCTAs, which are ZIP code areas with some small ones merged.)

I didn’t try to make the weight categories too fine-grained. Again, the weights are derived from the breed standard, not individual dogs, and so the distribution is quite lumpy. Each dog is counted as having the typical weight of its breed. Very popular breeds therefore pile up on single values. Many ZIP codes have a median of exactly 12.5 pounds, for example. (That’s the Shih Tzu’s weight.)

Even so, we still see a clear pattern. The ZIP codes with the biggest dogs are in lower Manhattan and brownstone Brooklyn. Park Slope is at the top, with a median of 29 pounds. Woodlawn and City Island in the Bronx, and the Rockaways in Queens, also have big dogs. The smallest dogs are in most of the Bronx, southeast Queens, and East New York and Brownsville in Brooklyn. There, the median dog weighs 12.5 pounds.

So Bill’s idea is partly supported by the evidence. Some of the city’s edges, where people have more room on average, do have bigger dogs. But, on the other hand, some of the densest apartment neighborhoods in the city have the biggest dogs of all.

Size classes

A median can hide a lot. I sorted the breeds into five size classes. I used the weight bands that you see on bags of dog food: Toy (up to about 9 pounds), Small (9 to 22), Medium (22 to 55), Large (55 to 99), and Giant (over 99). This is kind of arbitrary, and not even arbitrary in the “AKC Standard” sense of arbitrary. But I don’t think it’s unreasonable.

Across the city, here is how the dogs with a known size divide up:

• About a quarter are Toy dogs.
• About a third are Small.
• About a quarter are Medium.
• 14 percent are Large.
• Fewer than 2 percent are Giant.

Here is the share of each class within each ZIP code.

Toy dogs are most common in the Bronx and in parts of Brooklyn and Queens. Medium dogs cluster in somewhat fancier parts of Brooklyn and lower Manhattan. Large dogs are most common on Staten Island, in the Rockaways, and (again) in parts of Manhattan. Giant dogs are rare everywhere.

The same numbers aggregated up to the level of boroughs are a little easier to compare:

Small dogs are about a third of all licensed dogs in every borough. The differences are at the ends. A third of the Bronx’s dogs are Toy dogs, compared with about a fifth of Manhattan’s. Only 9 percent of the Bronx’s dogs are Large, compared with 16 percent in Manhattan and 17 percent on Staten Island. Staten Island, the least densely-populated borough, has the largest share of big dogs.

Mo Money, Mo Doggo

Manhattan and brownstone Brooklyn are dense, but they are also rich. The Bronx is dense too, but much poorer. Happily, thanks to both NYC OpenData and the Census Bureau, we have relevant housing and income measures available that we can construct for each ZIP code.

• Floor area per home. This comes from PLUTO, the city’s database of every tax lot. I added up the residential floor area and the number of homes on every lot in each ZIP code, and divided. This is gross floor area, so it includes halls and stairs. It’s a rough measure of apartment size. You can use my nycpluto package to access these data in R.
• Percent of homes in one- or two-family houses. This is also from PLUTO, using each lot’s building class.
• Median rooms per home, percent of homes that are owner-occupied, and median household income. These come from the Census Bureau’s American Community Survey, using the five-year estimates for 2020 to 2024. You can query the Census API directly for these, or use my nycdemog package to get them.

The Census reports these figures for ZCTAs, its version of ZIP code areas. Most MODZCTAs contain only one ZCTA. Where a MODZCTA contains more than one, I added up the counts. For the medians, I took an average of the ZCTA medians, weighted by the number of households. The Census caps median income at $250,000. A few of the richest ZIP codes in Manhattan hit that cap.

I fit a regression with this data where the outcome is the typical weight of the dogs in each ZIP code. I use an average rather than the median here, because the median is so lumpy. Specifically, I average the logged weights, which is the same as taking the geometric mean. Breed weights are very skewed. The middle dog weighs about 17 pounds, but a few breeds weigh well over 100. And differences in weight are proportional. Five pounds is a big difference between two toy dogs, but not between two retrievers. On the log scale, effects become percent differences in weight. The predictors are the five measures above, plus the borough. There are 177 ZIP codes in the model.

The five measures use different units: dollars, square feet, rooms, and percentages. This makes the coefficients hard to compare directly. What we can do is ask “If we take a ZIP code that is low on this measure (at the 25th percentile of ZIP codes) and move it to a high value (the 75th percentile), holding everything else constant, by what percent do its dogs get bigger or smaller?” For the boroughs, the figure shows the difference between each borough and Manhattan.

Income is the clearest result. A ZIP code with a median household income of $116,000 has dogs that are about 17 percent heavier, on average, than one with a median income of $67,000. The housing measures make much less difference once we know income, and they do not point the way Bill expected. The share of homes in one- or two-family houses and the share of owners have effects close to zero. Median rooms has a small positive effect, maybe, with an interval that includes zero. Floor area per home has a small but clearly negative effect. Moving from about 910 to about 1,100 square feet per home goes with dogs about 3 percent smaller, at the same income. Together, the four housing measures do improve the model a little, by more than we would expect by chance. But mostly that is the floor area effect, and it runs the wrong way for the idea that more room means bigger dogs.

Among the boroughs, Staten Island’s dogs are about 10 percent heavier than Manhattan’s at the same levels of income and housing. That fits the idea of room on the periphery, although the interval is wide, running from about 1 to 20 percent. The other boroughs do not differ much from Manhattan.

In terms of how much variation we can explain, income alone accounts for about 53 percent of the variation in typical dog size across ZIP codes. Adding the borough raises that to 54 percent. Adding all four housing measures raises it to 57 percent.

Here is the income effect on its own. This is a partial regression plot. For both dog size and income, we remove the part that the borough and the housing measures predict. What remains shows the relationship between income and dog size among ZIP codes with similar housing in the same borough.

The relationship is pretty good. Each doubling of median household income goes with dogs about 22 percent heavier. The points come from every borough. So there is a size gradient, as Bill speculated, but it’s not really geography at work here, it’s money. Some of the biggest dogs in New York live in dense, expensive neighborhoods such as Park Slope, SoHo, and the West Village. The smallest dogs live in the Bronx, where incomes are much lower. Once we know a ZIP code’s income, its housing tells us only a little more about its dogs, and not in the expected direction. If anything, more floor area per home goes with slightly smaller dogs. Staten Island is the one place where extra room may add to dog size, beyond what income predicts.

Again, as a paid-up social science rather than infographic guy, I feel like I have to close with the caveats. Remember these are breed weights, not dog weights. Four in ten dogs have no breed size. And, like we said before, these are the licensed dogs only. Licensing rates probably vary with income too. Finally, this is a comparison of ZIP codes, not of households. It tells us that richer ZIP codes have bigger dogs on average. It does not tell us that richer people choose bigger dogs, although that seems likely.

Why would money matter more than space? Big dogs cost more to feed and to treat at the vet. They are harder to keep in buildings that limit pets by weight. And their owners may need to pay someone to walk them while they are at work. Perhaps those many daily dog visits to Central Park are part of the answer too. If you live near a very large park, maybe it’s easier to have a very nice apartment that’s comparatively small for your very large dog.