There's a hidden wire stretched above Manhattan

Manhattan is just one of hundreds of metropolitan areas in the United States that has an eruv, which is a wire that symbolically turns public spaces into private spaces during the Jewish Sabbath.

From Mental Floss:

On the Sabbath, which is viewed as a day of rest, observant Jewish people aren't allowed to carry anything books, groceries, even children in public places (doing so is considered "work"). The eruv encircles much of Manhattan, acting as a symbolic boundary that turns the very public streets of the city into a private space, much like one's own home. This allows people to freely communicate and socialize on the Sabbath and carry whatever they pleasewithout having to worry about breaking Jewish law.Along with everything else in New York City, the eruv isn't cheap. It costs a group of Orthodox synagogues $100,000 a year to maintain the wires, which are inspected by a rabbi every Thursday before dawn to confirm they are all still attached.