The Invisible Eruv Wire Around Many American Cities
If you look up in many American cities, you may notice a transparent wire. This little wire actually serves a religious purpose. Known as an eruv wire, it acts as a loophole for Jewish religious law. On the Sabbath, Jewish religious law prohibits carrying items outside of the house. The eruv enclosed the Jewish neighborhoods in cities, so Jews can carry items outside their houses (but within the enclosed area) on the Sabbath.