Since the streets of our community do not run straight from one end of the city to the other ― they are not mefulashim u’mechuvanim m’shaar l’shaar.
Most poskim use the term mefulash m’shaar l’shaar without differentiating between a walled city and an open city (see also Mefulash According to the Shulchan Aruch). Since this is a very important distinction and has a great impact in how we apply the criterion of mefulash, we can garner from this omission that there is no difference halachically whether or not the city is walled.
The following is a partial list of poskim who are clearly not referring to a walled city:
- The Mishnah Berurah (364:8), when describing the cities of his times, stated that there were streets that were sixteen amos wide and mefulash m’shaar l’shaar. Therefore, a Baal Nefesh should be stringent since to erect an eruv in these cities they had to rely on the fact that the street did not have shishim ribo traversing it. As we know that most towns in his times were not walled ― even in earlier times most cities were not walled, Pri Megadim (Mishbetzes Zahav 362:17) ― we can deduce that he accepted the criterion of mefulash as not being dependent on a walled city.
- The Divrei Malkiel (4:3) states that to find a street in a large city which is mefulash, open from one end of the city to the other, is unheard of and that is why the minhag is to erect eruvin even in the largest of cities. He wrote this teshuvah regarding Odessa, a city that was not walled.
- Rav Shlomo Dovid Kahane zt”l (Divrei Menachem, O.C. vol. 2, pp. 42-43), one of the main rabbanim of Warsaw before World War II, posited that the heter to erect an eruv in a large city such as Warsaw, which was not walled from the year 1877 (Encyklopedia Warszawy, 1994 p. 187), was universally accepted as the streets were not mefulashim u’mechuvanim m’shaar l’shaar. More so, he claimed, a small city would have a greater problem establishing an eruv since its streets would be mefulash. In a small city there is usually one main street running straight through the center of the town as opposed to a large city where the streets are generally not straight from city gate to city gate.