Brooklyn as a Single City

Brooklyn contains neighborhoods with strong names, distinct communities, and recognizable local boundaries. Halachically, however, a neighborhood name does not automatically turn Flatbush, Boro Park, Crown Heights, or another section into a separate small town. Rav Moshe Feinstein's Brooklyn responsa begin from the urban reality that these neighborhoods form parts of one continuous city.

This is important to his discussion of shishim ribo. If the relevant question were always limited to the population of one named neighborhood, drawing a smaller line around a proposed eruv could appear to solve the problem. Rav Moshe did not accept that approach as a general rule.

"Brooklyn, which is one city"

In Igros Moshe, Orach Chaim IV:87, Rav Moshe develops his understanding of the requirement of six hundred thousand from the encampment in the Midbar. He distinguishes a single road from a city. For a road, the issue can be six hundred thousand passing there each day. In a city, he writes, the public character can be created by the people found throughout its streets even though each individual street contains far fewer.

He then turns directly to Brooklyn:

Therefore, in Brooklyn, which is one city filled with population, although it may be more than twelve mil by twelve mil, one must estimate, for example, Flatbush extending together with Brooklyn for twelve mil, whether enough people are found there that throughout all the streets of those twelve mil there are six hundred thousand. It is then a complete reshus harabim even according to those who require six hundred thousand.

The twelve-mile measure expresses what Rav Moshe understands the Midbar model to require. The area and the public found throughout its streets are considered together. Flatbush, in his example, remains part of the continuous Brooklyn city.

The relevant urban area

Rav Moshe takes the twelve-by-twelve-mil measure from the size associated with the Israelite encampment. His discussion therefore asks how the population is distributed over a comparable urban area. He adds that if six hundred thousand are found in a smaller area, the case is stronger. Conversely, if the entire relevant area does not contain the number needed to produce six hundred thousand people in its streets, his own calculation may yield a different result.

This is one reason his view cannot be summarized as "Brooklyn has more than 600,000 residents." Brooklyn did have far more than 600,000 residents, but Rav Moshe was addressing a more particular question. He was trying to translate the public reality of the Midbar into the geography and daily life of a modern city.

Dense housing mattered to him. New York and Brooklyn contained multistory apartment buildings with many families on a relatively small footprint. Rav Moshe contrasts that with the dispersed tents of the Midbar and reasons that a dense city can place very large numbers of people within a comparatively small area.

IV:88 adds the map and population premise

In Orach Chaim IV:88, dated 4 Shevat 5739 in the printed responsum, Rav Moshe returns to Flatbush. He says that in a large city like Brooklyn, a person who wants to permit an eruv on the ground that the necessary population is absent has to establish that factual premise. He viewed the city's size and density as making the opposite estimate plausible.

Later in the responsum he records that a map supplied by the city showed, as he understood it, that all of Brooklyn was approximately twelve mil by twelve mil and a little more. He writes that close to three million people lived there permanently and that close to another million entered for commerce, visits, and regular work. On those facts, he concluded that there were certainly far more than six hundred thousand in the streets of the relevant area.

The official decennial census counted 2,602,012 Brooklyn residents in 1970 and 2,230,936 in 1980. Those figures do not exactly match Rav Moshe's estimate of close to three million permanent residents. They should not be made to match artificially. The proper reading is that Rav Moshe stated a factual premise available to him and applied his halachic method to it, while the census supplies a separate historical measure of resident population.

One city and separate sections are not contradictory

Orach Chaim V:28 adds a second layer. Rav Moshe again says that an eruv cannot be made in Brooklyn, even in one part such as Flatbush, and that the same applies to Boro Park. He then writes that each significant section, "such as Flatbush and Boro Park and the like," is a reshus harabim independently because, on his factual premise, each has six hundred thousand within an area smaller than twelve by twelve mil.

At first glance, that can sound different from IV:87, which treats Flatbush as extending together with Brooklyn. The two passages address two ways the same city can meet his test. A neighborhood cannot simply ignore the surrounding continuous city, but if a particular section independently contains the necessary public population in the relevant area, it does not need the rest of Brooklyn to establish its status either.

Rav Moshe therefore did not make the Brooklyn question depend on one arbitrary neighborhood boundary. His analysis can run outward from Flatbush into the continuous city, or inward to a sufficiently populated section, depending on the facts.

What neighborhood boundaries can and cannot do

Local boundaries still matter for an actual eruv. A proposed enclosure has physical lines. The validity of those lines, the presence of walls or gaps, the streets that cross them, and the area actually enclosed all require examination. Rav Moshe himself discusses claimed surrounding walls and other physical features in V:28.

What a neighborhood line cannot do, in his analysis, is change the character of the streets simply by giving the enclosed area a smaller name. A Brooklyn neighborhood remains inside Brooklyn. If the surrounding urban area is a reshus harabim, or if the section itself meets the criteria for reshus harabim, a tzuras hapesach drawn around the neighborhood does not answer that problem.

That principle is directly relevant to Crown Heights. The local physical boundary requires its own detailed analysis, but the reshus harabim question begins before one reaches any particular utility pole. It begins with the kind of city and public area in which those poles stand.