Population and Public Streets in Brooklyn
Brooklyn's population matters to the halachos of reshus harabim, but the number printed in a census table is not, by itself, Rav Moshe Feinstein's test. His Brooklyn responsa distinguish residents from people actually found in the public streets, consider people entering the city from elsewhere, and examine how the streets of a dense modern city are used.
That distinction is essential. Saying that "Brooklyn had more than 600,000 people" is historically true but halachically incomplete. Saying that one particular avenue did not carry 600,000 people a day is also incomplete under Rav Moshe's city analysis.
Brooklyn's historical resident population
The U.S. Census figures compiled by the New York City Department of City Planning show the scale of Brooklyn across the decades surrounding Rav Moshe's major eruv responsa:
| Census year | Brooklyn population |
|---|---|
| 1940 | 2,698,285 |
| 1950 | 2,738,175 |
| 1960 | 2,627,319 |
| 1970 | 2,602,012 |
| 1980 | 2,230,936 |
| 1990 | 2,300,664 |
Rav Moshe's Flatbush responsa in Orach Chaim IV:87 and IV:88 were written in 5738 and 5739, between the 1970 and 1980 censuses. His extended response concerning Flatbush and Boro Park in Orach Chaim V:28 was written in 5741. Brooklyn was therefore a borough of well over two million residents throughout the immediate period.
These figures are useful as historical facts. They are not a substitute for reading the responsa, because Rav Moshe's discussion asks who is present in the streets and over what area.
A road and a city are not counted in exactly the same way
In Orach Chaim IV:87, Rav Moshe writes that there are two different settings. For a road, according to the opinion requiring shishim ribo, the familiar formulation is that six hundred thousand pass there every day. A city, he argues, can be a reshus harabim when six hundred thousand are found throughout the city's streets during the ordinary hours when people go out for their needs, even though no one street contains anything close to that number.
His model is the encampment in the Midbar. The people were spread through the camp, not continuously marching down one roadway. The camp nevertheless supplied the paradigm for reshus harabim. Rav Moshe therefore reasons that the public population of a city can be distributed among many streets.
He gives Flatbush and Brooklyn as the practical application. In the relevant area, one asks whether the people found throughout the streets reach the required number. If one particular street itself has six hundred thousand passing through it, he adds, that street can be a reshus harabim even if the city as a whole is smaller.
The broader disagreements about whether shishim ribo is required at all, what "every day" means, and how other poskim define the criterion belong to the full treatment of shishim ribo. Rav Moshe did not require six hundred thousand people to squeeze through the same Brooklyn avenue before the city could have the status of reshus harabim.
Dense housing changes the practical estimate
Rav Moshe repeatedly points to the density of New York housing. In the Midbar, families occupied tents spread over a broad area. In Brooklyn, a single apartment building could contain many families stacked vertically on a small parcel of land. Blocks of multifamily buildings therefore placed a very large resident population within a limited geographic area.
That observation appears in IV:87 and becomes part of the burden he places on a proposed leniency in IV:88. He writes that in a city as large as Brooklyn, someone who wishes to rely on the absence of six hundred thousand in the relevant area has to establish the facts, because ordinary estimates could readily put the number at or above the threshold.
Rav Moshe also acknowledges factual uncertainty. He did not present his urban estimate as a census bureau calculation. At one stage he says he had been told reliably that a particular twelve-by-twelve-mil area did not contain the necessary number. He still expressed concern that ordinary people, who would not know such measurements, could misunderstand an eruv there as proof that tzuras hapesach works even in an undisputed public domain.
Later in IV:88 he reports a city map and a different factual picture for Brooklyn as a whole: approximately twelve mil by twelve mil and a little more, close to three million permanent residents, and close to another million entering for regular urban purposes. On that premise he considered the case clear.
People who enter Brooklyn can count
Rav Moshe does not limit the city to people who sleep there. In IV:87 he discusses people entering from other cities and says they can join the calculation when their presence brings the public number to the required level. In IV:88 he specifically mentions those entering Brooklyn for business, visiting relatives, and regular work.
This does not mean that any tourist who ever visits Brooklyn is automatically added to a census total. His discussion concerns the number of people present in the public urban area, and elsewhere he distinguishes ordinary cities from exceptional destinations whose population swells because people travel there from around the world. The details of that distinction are part of his wider treatment of shishim ribo and large cities.
For Brooklyn, however, commuters and other regular entrants were not invisible. A city whose streets are used every day by large numbers of nonresidents can have a public reality larger than its resident count alone suggests.
Cars do not make the public disappear
A modern Brooklyn street is full of people traveling in vehicles. In Orach Chaim V:28, Rav Moshe answers an argument that the people inside cars should not count because the interior of a sufficiently sized vehicle can itself have the status of reshus hayachid.
He rejects the conclusion. The vehicle is not a fixed private home planted in the roadway. It exists to carry people through the public street. For the question of public passage, he writes, those riding in cars are counted as people traveling through the road.
The distinction is important because otherwise a city could become less public as its streets became busier. Rav Moshe considered that result contrary to the purpose and function of the streets.
Traffic laws facilitate public passage
V:28 also addresses traffic lights and stop signs. The fact that government rules tell drivers when to stop, where to turn, or how fast to travel does not make the street private or closed to the public. Rav Moshe writes that these regulations are the means by which cars and people can move through the city in an orderly fashion.
A public domain does not require every individual to be free to walk or drive in any direction at any speed. Public use can be heavily regulated and still be public use.
This point also bears on the requirement of mefulash streets. Rav Moshe concludes that the requirement for aligned gates or a straight route from one city gate to another is relevant to a city surrounded by walls. In Brooklyn and similar American cities without a surrounding city wall, he does not require one straight gate-to-gate avenue in order to classify the city as reshus harabim.
Sidewalks are part of the street system
Rav Moshe is equally explicit about sidewalks. In V:28 he includes them in the reshus harabim itself because they were made for the public to walk upon.
Cars parked along the curb do not permanently narrow the street either. They are temporary and constantly changing. Nor do moving cars create stable walls along the roadway. The physical width and enclosure of a street have their own halachic rules, but ordinary traffic does not transform a broad public avenue into a narrow private corridor.
What the numbers can establish
The historical census data establish that Brooklyn was a very large borough. Rav Moshe's responsa establish how he believed the public population of such a city should be translated into the halachic category of reshus harabim. The two sets of information should be read together without confusing them.
The census cannot prove how many people were in Brooklyn's streets at a particular hour in 5739. Rav Moshe's estimate cannot replace the census as a historical resident count. What his rulings do show clearly is that he regarded Brooklyn's enormous resident base, dense housing, commuters, visitors, cars, sidewalks, and interconnected public streets as part of one practical halachic problem.