A Street Sixteen Amos Wide

Sixteen amos is one of the basic measurements in the halachos of reshus harabim. When a city street is being considered as a possible Torah-level public domain, its width is therefore an essential question. The measurement has a direct source in the Gemara and appears throughout the later definitions of reshus harabim.

Width, however, is one element within a larger halachic definition. The sources also discuss where the road leads, whether it is roofed or enclosed, how it is used by the public, and, according to an important group of Rishonim and Poskim, shishim ribo. They also discuss cases in which a public road narrows without losing its status.

The sixteen-amah measurement comes from the Mishkan

The Gemara in Shabbos 99a derives the width of a reshus harabim from the route used by the wagons in the Mishkan:

דרך רשות הרבים שש עשרה אמה

“The width of a reshus harabim is sixteen amos.”

The Gemara calculates the space occupied by the wagons, the space between them, and the additional room needed alongside them. This becomes the classical source for the sixteen-amah width.

The Rambam accordingly defines the public roads of reshus harabim with the condition that “the width of the road be sixteen amos” and that it have no roof (Hilchos Shabbos 14:1). He later states that a reshus harabim which has a roof, or whose width is less than sixteen amos, is treated as a karmelis (14:6).

The Shulchan Aruch begins its definition in the same way: “streets and marketplaces that are sixteen amos wide,” provided the other conditions in the se'if are met (Orach Chaim 345:7).

The Alter Rebbe gives different formulations for streets, roads, and mavo'os

The Alter Rebbe's wording in Orach Chaim 345:11 is especially useful because he lists several kinds of public routes separately.

He first describes streets and marketplaces as sixteen amos by sixteen amos. He then includes roads used to travel from city to city when they are sixteen amos wide. He also includes mavo'os sixteen amos wide that are mefulash from one street to another, or from streets into roads that are themselves sixteen amos wide.

These are related categories, though their descriptions are not identical. A broad public square or marketplace is described as an area. A road between cities is described by its width. A mavo'i is described by both its width and the public routes into which it opens.

The same se'if also records the opinion that a place is not a reshus harabim unless shishim ribo pass through it every day. That separate question is addressed in the pages devoted to shishim ribo. The sixteen-amah rule exists in the text before that additional opinion is introduced.

A public road can narrow

A common oversimplification treats every short section of a route as though it must independently maintain a full sixteen-amah width. The Shulchan Aruch and the Alter Rebbe discuss narrower continuations expressly.

The Shulchan Aruch, Orach Chaim 345:8, records an opinion that mavo'os which are sixteen amos wide and become narrower in part can retain the status of reshus harabim when they run along the length of a reshus harabim.

The Alter Rebbe states the principle more fully in 345:12. A mavo'i open to reshus harabim at both ends, running in the same lengthwise direction as the reshus harabim, can itself be a complete reshus harabim even when it is less than sixteen amos wide. He explains why:

לפי שהן כרשות הרבים ארוכה שנתקצרה בקצתה

“They are like a long reshus harabim that became narrower in part.”

He immediately limits that formulation. If the mavo'i runs across the width of the reshus harabim, it does not receive the same status under that opinion merely by being connected at its ends.

The Alter Rebbe then records another opinion requiring such a narrower mavo'i to be at least thirteen and one-third amos wide. Under that view, a mavo'i of that width can be a reshus harabim even when it runs across the width of the larger reshus harabim.

The Rosh, quoting Rabbeinu Yitzchok, gives the underlying case in more concrete terms: a mavo'i thirteen and one-third amos wide, whose two ends open into a sixteen-amah reshus harabim, can be considered a Torah-level reshus harabim “since the public passes through it” (Eruvin, chapter 1).

Sixteen amos is a rule of width, not a complete definition by itself

A road sixteen amos wide has satisfied a major physical measurement. That fact alone does not answer every other part of the definition of reshus harabim. The same siman of Shulchan Aruch discusses walls, gates, roofs, narrower continuations, public routes, and the opinion requiring shishim ribo.

The reverse is also important. A narrow point does not automatically remove an entire public route from the category. The Poskim discuss when a narrower stretch is viewed as part of the longer reshus harabim and when the direction, width, and public connection of the narrower route require separate analysis.

For a modern city, the practical question is therefore more exact than simply measuring one cross-section of pavement. One must identify the halachic route being discussed, measure its relevant width, and then apply the rules for its connections, enclosure, and public use under the particular shita being followed.