There is an interesting article in this morning's New York Times, A Jewish Ritual Collides With Mother Nature, dealing with eruvim. You probably ask, "What the heck is eruvim?" An eruv (eruvim is the plural) is an enclosure around a community within which Orthodox Jews may carry objects on the sabbath. The eruv extends the boundary of one's home to the entire eruv. The boundary may consist of walls, wires and posts. It is important for Orthodox Jews to know the boundary of the evru. The Wikipedia article on Evru notes, "Without an eruv, Torah-observant Jews would be unable to carry keys or tissues in their pockets or push baby carriages on the Jewish Sabbath thus making it difficult for many to leave home." The Times article describes the havoc wreaked among the orthodax community as a result of the recent blizzards in the northeast.
There is a Eruv in the Boca Raton area near our area (although we are not included in the Eruv) and I have noticed a wire strung from street light poles along Glades Road. The Boca Raton Eruv area is this:
The Eruv for Rochester, NY is as follows:
A list of eruvim can be found at Wikipedia.