Study Eruvin folio 55B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
One allocates a karpef to every city, i.e., an area of slightly more than 70 cubits is added to the boundary of a city and the Shabbat limit is measured from there; this is the statement of R' Meir. And the rabbis say: They spoke of the measure of a karpef only with regard to the space between two
And it was stated that the amora’im disputed this issue. Rav Huna said: A karpef is added to this city and another karpef is added to that city, so that as long as the cities are not separated by a distance of slightly more than 141 cubits, they are considered one entity. And Ḥiyya bar Rav said: One
The Talmud answers: It is necessary for Rav Huna to state this halakha in both instances, as, had he taught it to us only here, in the case of the breached wall, one might have said that a karpef is allocated to each city only in that case because it had an aspect of permissibility from the outset,
And had he taught it to us only there, with regard to the two cities, one might have said that only in that case is a karpef allocated to each city because one karpef would be too cramped for the use of both cities. But here, in the case of the breached wall, where one karpef would not be too cram
The Talmud asks: And how much distance may there be between the imaginary bowstring and the center of the bow in a city that is shaped like a bow? Rabba bar Rav Huna said: 2,000 cubits. Rava, son of Rabba bar Rav Huna, said: Even more than 2,000 cubits.