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Comment by tuan | Hacker News Reader

this reminds me of issue I had when I heard American on TV or movies use number of blocks to describe a distance, for example: "my house is three blocks away from here". I thought block is a unit, just like meter or kilometer. I've wondered for a long time how many meters in a block there are. Just for comparison, in Vietnam, we say something like "my house is about 100m away from here" or something like that. If you look at the map of city like Hanoi, Vietnam, you'll see why we cannot use "blocks" to describe distance.

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> I thought block is a unit, just like meter or kilometer.

It is a unit, the distance between streets, but it varies widely across boroughs/districts in a single city or other municipality, and they aren’t really a reliable indicator of distance between different cities, though they are vaguely walkable for most places and people.

From Oxford Dictionary:

> (North American English) the area bounded by four streets in a town or suburb

> (North American English) the length of one side of a town block, typically as a measure of distance

It's only a very vague distance in many places in the US as well, but it's typically between 100 and 200 meters.

In Manhattan (a popular location for US mass media) a block running north-south is 80 meters, but an east-west block is variable and about 250 meters.

Chicago also uses a rectangular block, but with east-west blocks being shorter at 100 meters and north-south blocks being 200 meters.

Where I live, a block is 160 meters downtown (10 blocks to a mile).

Interesting. I didn't know that. Do you do the conversion in your head, like 2 blocks = 160*2 meters, when someone use blocks in a conversation ? Just curious.

also ... LOOK everyone I found an American who uses metric system as first choice in their post!!!

The Chicago grid is actually based on fractions of a mile (1/8 and 1/16 iirc), and when I lived there I would absolutely convert blocks to miles automatically when talking to people.

I think it's more navigational? like I know "oh, I'd cross three streets and then be at the house" roughly, more than thinking about distance. It kinda equals effort to walk there and how often you'll stop for traffic more.

This right here. Nobody is converting the local average distance between streets in their heads into ordinary units of length and then converting. In ordinary conversation, to say "so-and-so is three blocks away" means you'd need to cross three streets to get there.

And just like you have an idea of how big a mile or kilometer is without having to get out a tool to measure it, blocks tend to be pretty consistent within a given town or city, so "a block" has a similar rough intuitive distance.

> Interesting. I didn't know that. Do you do the conversion in your head, like 2 blocks = 160*2 meters, when someone use blocks in a conversation ? Just curious.

I do it explicitly some times, but mainly I do 2 blocks -> 5 minutes of walking.

It's also useful to think in blocks because addresses here (and in many places in the US) go up/down by 100 for each block; so if I'm going from 12XX to 7XX (colloquially "The 1200 block to the 700 block") that's 5 blocks.

> also ... LOOK everyone I found an American who uses metric system as first choice in their post!!!

Meters are better than feet in every way even if you use miles for long distances. There are 5280 feet in a mile, but 1600 meters in a mile[1]. One of these numbers is far easier to deal with.

As an aside, I wonder about using centimeters for height; In the US, if you look at a bell-curve for "self reported height of men" you see a drop off just below 6' (~183cm) and a huge spike at 6', distorting the curve[2]. Do you see similar distortions at 180 or 175cm in countries where the metric system is used? Given that far more men are "almost" 180cm or 175cm (in the US, 175 is average) are there more men "rounding up" on their heights in such places?

Athletes, in particular, are incentivized to round-up, as scouts won't even look at you if you are "too short" and scouts like to use even numbers for cutoffs.

1: Technically 1609, but that makes an eighth of a mile estimate off by only about a meter, and the "mile run" event in US high-school track is actually 1600 meters.

2: The center of the bell-curve is also 2-3cm taller than measured heights of men in the US.

> Do you see similar distortions at 180 or 175cm in countries where the metric system is used?

No idea, but Vietnamese avg height is 168 cm :D I cannot find any sources published by our gov that has height distribution info.

>Meters are better than feet in every way even if you use miles for long distances. There are 5280 feet in a mile, but 1600 meters in a mile[1]. One of these numbers is far easier to deal with.

why have you forsaken the furlong, the chain, and the rod?

Two reasons:

1. To use all 3 would require remembering more conversion ratios

2. More people (even in the US) are familiar with meters than those units. I was not familiar with the Rod at all, which is the closest to meter in utility for discussing block lengths.

I'm 69" tall, and I wonder if that would be a spike of its own if we didn't use a combination of inches and feet.

There is always a bit of a surprise to it, because it can apply equally to really long blocks in the suburbs or really short blocks in a town.

Usually when I use blocks, in the US, in conversation, it's with a city that both of us are familiar with. Any conversion to other units makes less sense in my head than the visual idea of what I know the city looks like outside.

I usually hear it's N avenues away if you need to walk east-west in Manhattan.

The block definitely has a New York center of gravity in the American conception. The Manhattan street grid is very regular with “short blocks” and “long blocks” and vast swaths of the rest of the city use a very similar approach.

There’s also certainly an element of it that comes from all the other gridded cities especially Chicago and the older cities of the East and Midwest.

But New York is one of the most written and talked about and filmed places on the planet and I suspect that’s the biggest cause of it being considered standard American English.

I don't think it entered parlance through that usage. It was actually a common feature of the landscape beginning in the 1780s [2] even if we don't count Philadelphia in the 1680s [3] which later became the national capital city.

The Commissioners' Plan which griddified Manhattan was not until 1811 -- but tens of thousands of square miles were already being rapidly surveyed into townships, sections, and ranges, which lend themselves to further square subdividing, after an act of congress back in 1785.[1]

As a fun side note, 19th Century Philadelphia invented the process of adding street numbers to its existing grid using 100-to-a-block addressing, and was also the first American city to add the hundred-block to street signs.

[1] https://en.m.wikipedia.org/wiki/Seven_Ranges

[2] https://www.bloomberg.com/news/articles/2015-09-16/the-jeffe...

[3] https://dougalleninstitute.org/archives/10148/

[4] https://www.ncesc.com/geographic-pedia/what-is-the-philadelp...

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