There are many better or worse maintained maps of eruvei chatzeros available to the public, which are a boon to travellers to a new place interested in where they can move things outdoors during shabas, many of which are conveniently displayed or linked on the websites of local eruvin (cf.).

Has a similar effort been made to depict the edges of t'chumim - for travellers interested in moving near populated areas on shabas, or who might be stuck doing so for unforeseen reasons - on a map?

Bonus: two tags beginning with 'tech'!

  • I have to say, this is one of the better questions that I have seen in quite some time. B"N, I'm asking at least one neighborhood rav this question. BTW, I'm uncertain about your use of the "technology" tag, as I don't think techum is "technology". However, perhaps, you're referring to, say, a map on "smart" phones? – DanF Apr 1 '16 at 13:17
  • I had in mind the unique cartographic circumstances - in any medium. Often mapmakers have to tread lightly when drawing up political boundaries when/because they don't correspond to physical structures, but in this case there is also the technical challenge of 2,000 ama projection at arbitrary angles from often nebulous population clusters. Ayen od – WAF Apr 1 '16 at 13:25
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    I agree about the measurement from different angles. Though, from my understanding, it would be from any city limit - wherever that border is. Though, admittedly, I know someone that walked from inside Nassau County, NY to mid Brooklyn - a distance of about 10 miles. I'm not sure how that didn't violate the techum. – DanF Apr 1 '16 at 13:33
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    I'll bet there are religious yishuvim in Israel that maintain such maps. – Isaac Moses Apr 1 '16 at 15:53
  • @IsaacMoses What yishuvim are popular for the cartographically inclined? I would look there first. – WAF Apr 1 '16 at 15:55

No, generally no one makes maps of techumin because the techum only starts at the suburban/rural border. The techum Shabbos only starts slightly more than 70 amos beyond the last house of the yishuv. As long as there are houses/buildings within 70 amos (~140 feet/~43 metres), you are still within the yishuv and don't start measuring the 2000 amos of the techum (Shulchan Aruch Orach Chaim 398:6).

Since most people live within large populated areas, they would get tired of walking long before they would exit the techum. I would not be surprised if you could (theoretically) walk from Silver Spring to Brooklyn without ever leaving suburbia. Don't be confused: you could walk as long as you want, but you would be outside the eruv and unable to carry anything.

That said, from where I live in Ramat Beit Shemesh, you cannot reach many other places within the techum (the edge of Jerusalem is about 15 kilometers straight-line), so the techum map would potentially be useful. That map is majorly out of date.

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  • I guess you're implying that by definition the majority of people don't live/hang out near the edge of town, so aren't interested in producing such maps. Because for those people, 2070 amos is not really that long at all, especially for those living outside the Silver Spring-Brooklyn axis. – WAF Apr 6 '16 at 11:59
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    @WAF: Yes, that seems to be the case - for straightforward reasons. Most Jewish communities grow from a nucleus within older suburbs. Once the community is in a given location, services from shopping to schools to shuls will gravitate there - making moving somewhere far away a losing proposition. The community grows organically well behind the edge of expanding suburbia. I know of exactly one exception in North America: Thornhill, a suburb of Toronto, purpose-built by Joe Tanenbaum from farmland in the early 80s, and was then the real edge of Toronto - and everyone told him you can't do that! – Ari Heitner Apr 6 '16 at 18:02
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    So you would answer the question "yes". . . Aaaand my "arbitrary angles" hypothesis (comments above) is usually wrong. – WAF Apr 1 '16 at 16:48
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    Very interesting. Do you know what the blue and red borders mean? If you can, edit that into your answer. – DanF Apr 1 '16 at 17:02
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    I don't understand. That Bes Shemesh city boundary goes right through a set of buildings (on the left, I assume west, side). Are they abandoned or not yet settled, perhaps? – msh210 Apr 1 '16 at 17:37
  • @DanF and msh210, I share both of your non-understandings. – Isaac Moses Apr 1 '16 at 17:39
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    @msh210 The inner line too is squared off. That squaring might include houses which are not part of the locale and don't extend the inner line. Consider a town shaped like an L. A few extra houses in the top right corner would be well within the Techum (even within the "inner line" that 2000 Ammot is counted from), but not extend the town's size. – Double AA Apr 4 '16 at 4:11

I know that Lakewood NJ has a techum map, -they need one for walking to the new developnents that are not connected to the main part of town. I think lakewood and monsey also need one because they suburban and many parts of town have houses that are not within 70/140 amos of each other

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    Interesting. How far away are those developments? Can you link to a map? – WAF Aug 28 '16 at 19:01

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