“From an eruv perspective,” said Rabbi Yaakov Kermaier, president of the New York Board of Rabbis, “it was the perfect storm.”

Image Rabbi Adam Mintz, a historian of eruvim in the United States, displayed maps of the boundaries of eruvim in New York City. Credit... Ruby Washington/The New York Times

The damage to eruvim this winter evokes another kind of convergence, as well. It draws attention to the concept of the eruv itself, a combination of religious obligation, historical phenomenon and what academics call a social construction. In more than one way, an eruv is a through line.

“Eruv is one of the only Jewish practices that forces the Jew and the Jewish community to confront the broader world,” said Rabbi Adam Mintz of the Manhattan congregation Kehilat Rayim Ahuvim, who is writing a doctoral dissertation and book about the eruvim in North America. “This symbolic boundary around the neighborhood requires interaction with the broader community, whether it’s asking permission, renting space, putting up strings and poles in front of someone’s apartment.”

An entire tractate, or volume, of the Talmud deals with the eruv. As a practical matter, though, Jews in antiquity lived within walled cities whose protective barriers doubled for religious purposes. The ghettos of Europe, which penned Jews inside, also served as eruvim.

But with their emancipation in various European countries, as Rabbi Mintz noted in a recent interview, Jews began to create eruvim, first using natural boundaries like rivers and later technological markers like telegraph poles. One of the first eruvim in North America, formed on the East Side of Manhattan in 1905, used both the East River and the Third Avenue elevated train.

Still, the entire continent had only three eruvim until 1970. To Rabbi Mintz, that paucity betrayed a Jewish reluctance to bring an abstruse matter of ritual observance into the realm of public policy — in the form of municipal zoning or planning boards, or city councils. Meanwhile, he said, an increasing number of Orthodox Jews were simply carrying on the Sabbath, eruv or not.

The growing confidence of Orthodox Jews, and the vitality of their movement in an America replacing melting-pot assimilation with cultural pluralism, led to the rapid growth in eruvim over the last two generations. Rabbi Mintz has identified more than 150 in North America by their Web sites. Real estate agents seeking Orthodox homebuyers promote eruvim the way other brokers brandish SAT scores from the local high schools.