Eruvin5: 2
נוֹתְנִין קַרְפֵּף לְעִיר — דִּבְרֵי רַבִּי מֵאִיר. וַחֲכָמִים אוֹמְרִים: לֹא אָמְרוּ קַרְפֵּף, אֶלָּא בֵין שְׁתֵּי עֲיָרוֹת; אִם יֵשׁ לָזוֹ שִׁבְעִים אַמָּה וְשִׁירַיִם וְלָזוֹ שִׁבְעִים אַמָּה וְשִׁירַיִם, עוֹשֶׂה קַרְפֵּף לִשְׁתֵּיהֶן לִהְיוֹתָן כְּאַחַת.
We grant a karpeif to a town — [these are] the words of R’ Meir. But the Sages say: They did not say [the rule of] karpeif, except between two towns; if this one has seventy cubits and a fraction and that one has seventy cubits and a fraction, a karpeif is granted to the two of them to become as one.