Reshus Harabim in a Modern City

In any discussion of an eruv in Crown Heights, the first halachic question is what kind of reshus the streets are. An eruv cannot be evaluated from its poles, wires, or other boundary structures alone. The halacha first asks whether the area is a reshus hayachid, a karmelis, or a reshus harabim, because the answer determines what kind of enclosure can permit carrying there.

This is especially important in a large modern city. Wide streets, intersecting avenues, heavy public use, existing buildings and barriers, and the number of people who use an area can each enter the discussion. They do not all enter in the same way, and the major disputes among the Rishonim and later Poskim cannot be reduced to a single test.

The starting point in Chazal

The Gemara gives a compact description of a full reshus harabim:

איזו היא רשות הרבים? סרטיא ופלטיא גדולה ומבואות המפולשין.

What is reshus harabim? A seratya, a large platya, and mefulash passageways.
(Shabbos 6a)

A seratya is the kind of major public road used for general passage. A platya is a large public square or marketplace. Mavo'os hamefulashin are public passageways that run through from one side to another. These terms describe places whose character is public movement and public use.

The Rambam formulates the definition with several physical features. He includes public roads that are sixteen amos wide and uncovered, and he separately discusses a city surrounded by walls whose gates are closed at night. The Shulchan Aruch and the Alter Rebbe likewise begin with roads and marketplaces sixteen amos wide, together with the questions of roofing, walls, and whether a road passes through a walled city from gate to gate. (Rambam, Hilchos Shabbos 14:1; Shulchan Aruch, Orach Chayim 345:7; Shulchan Aruch HaRav 345:11.)

The definition therefore has several layers from the outset. There is the road itself, its width and physical form, the way it serves the public, and the effect of any enclosure surrounding the larger area.

Why the classification comes first

A tzuras hapesach is a genuine halachic partition. That does not mean that the same arrangement works in every type of domain.

The Alter Rebbe rules that, on the Torah level, a tzuras hapesach can function as a complete mechitza. He then states that Chazal did not allow an ordinary tzuras hapesach to permit carrying in a place that is a full reshus harabim. His formulation is direct:

אף על פי כן מדברי סופרים אין צורת פתח מועלת לרשות הרבים גמורה.
Nevertheless, under Rabbinic law, a tzuras hapesach does not suffice for a full reshus harabim.
(Shulchan Aruch HaRav 364:4.)

For such a reshus harabim, the discussion turns to actual delasos, with a further dispute about whether they must actually be closed at night or merely be capable of being closed. Those laws have their own details.

This is why the order of the analysis matters. One first determines the status of the public ways and the effect of any existing enclosure. Only then can one determine which method of enclosure is halachically sufficient. A proposed boundary cannot answer the earlier question by itself.

The detailed laws of physical enclosure and tzuras hapesach and gates and delasos are treated separately.

Sixteen amos, mefulash, and public use

Sixteen amos

Sixteen amos is one of the clearest measurements in the classical definition. The Rambam writes of a public road:

ובלבד שיהיה רוחב הדרך שש עשרה אמה, ולא תהיה עליו תקרה.
Provided that the road is sixteen amos wide and is not roofed.
(Rambam, Hilchos Shabbos 14:1.)

The Alter Rebbe similarly defines public roads and marketplaces as sixteen amos wide. The measurement is associated with the width of the public way in the machaneh in the midbar, the model from which the melachos and the domains of Shabbos are derived.

A modern avenue may have traffic lanes, medians, parking lanes, sidewalks, islands, or other features. Whether they combine, divide, or alter the relevant sixteen-amah width can require a more exact analysis. The general rule belongs here; the detailed measurement questions belong to the treatment of sixteen amos.

Mefulash

Mefulash describes a way that passes through or is open through. The word is simple; its application can be more complicated.

The Alter Rebbe distinguishes a city without a surrounding wall from a walled city. When a city is walled, he describes a sixteen-amah public road running from one gate to the opposite gate, with the gates aligned and not closed at night. Intercity roads and other public ways have their own formulation.

Rav Moshe Feinstein later emphasizes the same structural distinction when discussing Rashi. He explains that the requirement for gates or exits to be aligned in a straight line is tied to the case of a city whose surrounding wall would otherwise enclose it. An unwalled city is not automatically removed from reshus harabim because its streets bend or because the route out of the city is not aligned with an opposite gate. (Igros Moshe, Orach Chayim V:28, anaf 3.)

In a modern street grid, “mefulash” cannot be turned into a rule that every individual street must form one perfectly straight line across an entire metropolis. The exact forms of mefulash, straightness, openings, and intersections are treated in the dedicated discussion of mefulash.

Public use

The classical examples are public roads, marketplaces, squares, and passageways. Their defining use is public movement. A reshus harabim is therefore not identified by width alone. The way is one through which the public actually passes and which functions as a public way.

That does not reduce the question to legal ownership. A street may be publicly used although the underlying property arrangements are complicated, and a physically open area may still raise questions about whether access is genuinely public. Restrictions, gates, controlled access, dead ends, private compounds, and comparable conditions can affect the analysis in different ways.

The specific rules governing public access and public use are a separate part of the definition.

The dispute over shishim ribo

One of the major disputes is whether a full reshus harabim requires the passage of shishim ribo, six hundred thousand people.

The Rambam's basic definition of reshus harabim does not state such a requirement. The Shulchan Aruch first gives the physical definition of streets and marketplaces sixteen amos wide, then records a second opinion that an area is not a full reshus harabim unless shishim ribo pass through it each day.

The Alter Rebbe preserves that structure:

ויש אומרים שכל שאין ששים רבוא עוברים בו בכל יום אינו רשות הרבים אלא כרמלית.
There are authorities who say that where six hundred thousand do not pass each day, the area is a karmelis rather than a reshus harabim.
(Shulchan Aruch HaRav 345:11.)

The status of this requirement was already disputed among the Rishonim. Rashi uses the six-hundred-thousand model drawn from the machaneh in the midbar. Tosafos likewise records the requirement, citing the Halachos Gedolos while discussing the definition of reshus harabim. The Ramban challenges the requirement sharply, writing of Rashi's formulation:

ולא ידענו מנין לו לרש״י כן שלא הוזכר בתלמוד בשום מקום.
We do not know Rashi's source for this, since it is not mentioned in the Talmud.
(Chiddushei HaRamban, Eruvin 59a.)

The Ramban immediately notes that the rule does appear in the Halachos Gedolos, so the question is an old dispute among major authorities, rather than a modern attempt to redefine a city.

The Alter Rebbe records that the widespread practice was to rely on the opinion requiring shishim ribo and therefore to say that a full reshus harabim was uncommon in his time. He also writes that a yerei Shamayim should be stringent for himself. The meaning of the shishim-ribo requirement, what exactly must be counted, and how its different formulations are reconciled require their own treatment. Those questions are addressed under shishim ribo and “no reshus harabim today”.

A street and a city are different units of analysis

Modern-city discussions become confused when every criterion is forced onto the same geographic unit.

The sixteen-amah measurement describes a public way. Roofing likewise concerns the physical way itself. Public use can concern a street, road, square, or connected route. A surrounding wall may enclose an entire city or district. The law of a road running from gate to gate becomes relevant precisely because the city as a whole is enclosed. The various interpretations of shishim ribo raise a further question about what population or flow is being measured.

Rav Moshe's discussion in Igros Moshe Orach Chayim V:28 is particularly useful for keeping those questions separate. In explaining Rashi, he says that the straight, aligned-gate condition belongs to the walled-city case. For a city without a surrounding wall, the status of a wide public road does not depend on finding two opposite city gates. The street and the city's perimeter are therefore related questions, but they are not interchangeable.

The same discipline is necessary in reverse. A city may contain many narrow residential streets, yet that fact does not itself determine the status of its wider arterial roads. A single wide road likewise does not answer every question about the larger city's existing mechitzos or the status of other streets.

The precise halachos of street versus city are developed separately.

Physical enclosure can change the classification

Proper mechitzos can change the halachic status of the enclosed area.

This principle appears directly in the laws of reshus harabim. The Rambam treats a walled city whose gates are closed at night differently from an open public domain. The Shulchan Aruch and Alter Rebbe discuss when walls and gates remove a road from the ordinary definition of reshus harabim and when an open gate-to-gate road retains that status.

The Gemara in Eruvin expresses the underlying principle as כוחן של מחיצות, the halachic force of partitions. At the same time, the details matter. Openings, breaches, public roads through the enclosure, and the laws of delasos can determine whether the surrounding structures are effective for the purpose at hand. (Eruvin 22a.)

For that reason, one should not assume that a modern city is either enclosed or unenclosed merely from a map. Rivers, embankments, fences, walls, rail structures, buildings, and other features each have their own halachic requirements. Nor does the existence of some physical boundary remove the need to analyze the public roads that cross it.

Those rules belong to the pages on physical enclosure and gates.

How a modern-city question is organized

A careful analysis therefore proceeds in stages.

First come the public ways themselves: their width, whether they are roofed, the way they run through the area, and the character of their public use. These questions identify which streets or spaces could satisfy the classical description of reshus harabim.

Next comes the larger physical setting. Existing walls or other valid mechitzos may change the status of an area, while major openings or roads through an enclosure raise the laws of mefulash and delasos.

The shishim-ribo dispute then has to be stated on its own terms. One must identify which halachic position is being followed and, within the opinions that require six hundred thousand, what kind of passage or population satisfies that requirement. The arithmetic cannot be separated from the definition being used.

Only after those questions are answered can one ask what new enclosure is needed and whether the proposed method is sufficient. A tzuras hapesach, actual walls, and delasos do not all have the same law for every domain.

This framework is the starting point for the separate discussions of Manhattan, Brooklyn, and Crown Heights. Those pages apply the definitions to their own streets, populations, and physical boundaries. The halachic definition of reshus harabim develops the underlying criteria in greater detail.