Hi Rabbi Abadi,
1. Walking within a city: If neighborhoods are continuously connected, does the entire area count as one city for Techum Shabbat? For example, could someone walk across all of NYC on Shabbat, even if it’s many miles, as long as the neighborhoods are connected? What actually determines the halachic boundary of a city?
2. Traveling above ten tefachim: Why would traveling more than ten tefachim above the ground remove the issue of Techum Shabbat? Shulchan Aruch (OC 404:1) seems to treat this as a safeik. How does that translate into practical permission for someone sitting on a bus or train?
3. Arriving in another city: If someone travels outside their original Techum and arrives in another city on Shabbat, can they walk throughout that city? Does it matter whether they left intentionally or began traveling before Shabbat?
Thank you!
Techum Shabbos is a very large sugya, with extensive discussions in the Gemara, Rishonim, and Acharonim. Asking questions here should not replace learning the sugya properly.
1. Walking within a city
Generally, a person can walk throughout a halachically connected city, even if it extends for many miles. The boundaries are determined by the halachic rules for connecting buildings, neighborhoods, and cities, and by squaring off the city for calculating its techum. See Shulchan Aruch, Orach Chaim 398.
2. Traveling above ten tefachim
Please read the entire Aruch HaShulchan, Orach Chaim 404, especially sections 2–4.
He explains the underlying machlokes regarding whether twelve mil is a Torah prohibition and why the unresolved question of techum above ten tefachim is treated leniently according to the poskim who consider techumin rabbinic.
There are two separate uncertainties here, and they must be analyzed together.
Simply reading the Shulchan Aruch without studying the Rambam, Kesef Mishneh, Beit Yosef, and the other Rishonim does not give you the entire picture.
Whether a particular bus or train qualifies for the leniency is a separate question.
3. Arriving in another city
This involves another extensive sugya, including the laws of acquiring shevitah, leaving the techum intentionally or unintentionally, and entering a different city.
If you have a specific practical halachic question, please post the circumstances and I’ll be happy to address it.
But studying an entire sugya requires opening the Gemara and the Rishonim. It cannot be replaced by asking me to summarize everything on the website.
Thank you