The Position That There Is No Reshus Harabim Today
The expression that there is no reshus harabim today describes a halachic position formed in cities very different from modern New York. Its use depends on the conditions that made a Torah public domain uncommon: width, openness, gates, street form, and, according to many, shishim ribo.
Why a full reshus harabim was considered rare
Many medieval and early modern cities were enclosed by working walls and gates. Their streets were often narrow, crooked, closed at night, or used by populations far below shishim ribo. Under a definition requiring several of these conditions together, a complete reshus harabim could indeed be uncommon.
That historical reality supported communal eruvin where the streets were treated as karmelis. It did not abolish reshus harabim as a category or declare that future cities could never meet its definition.
The Alter Rebbe records both sides
Shulchan Aruch HaRav records the view requiring shishim ribo and the stricter view that does not. Elsewhere, the Alter Rebbe discusses cities and roads in relation to the population they serve.
The practical question is therefore not whether one familiar sentence can be quoted. It is how the accepted psak applies the Alter Rebbe's full presentation to the city before it.
The recorded Yerushalayim discussion
In the Rebbe's recorded meeting with Israel's Chief Rabbis, Rabbi Mordechai Eliyahu states his position that present-day streets do not require 600,000 and that there is no reshus harabim today. The discussion then turns to the Old City walls and the curved streets of newer Yerushalayim; the Rebbe interjects lo mefulash.
Rabbi Eliyahu is speaking about Yerushalayim according to his approach. Crown Heights and New York do not enter that exchange.
Modern New York must be judged in its actual form
New York combines a population far beyond the older cities, wide public roads, continuous access, a connected grid, bridges, tunnels, transit, and constant movement between neighborhoods.
Those facts do not decide every dispute among the poskim, but they must be addressed. The older expression cannot be used as a substitute for the modern city analysis performed by Rav Moshe and the Rabbonim who ruled on New York eruvin.