Longman cites an example with 'on' but it probably has a different meaning (part of the town lies on the one side of the border, the other part on the other).

a market town on the border of England and Wales

Here's a sentence from the Guardian, 'at' is used. This is a completely different context, though.

The establishment of supervisory mechanisms to ensure the humane treatment of migrants at the border [...].

Here's my example I need advice on.

South Ossetia is a small partially recognized country on the Russian South-Western border.

I think 'at' should be used (because it adjoins the border, not lies on it), but I'm not entirely sure.


3 Answers 3


On is used if something straddles the border. Like a house (such a thing does exist) or a town. If one part of the entity is in one country, and the other part of the entity is in another country, then it's on the border.

Niagara Falls is an example of a city that has part of it in one country (the US) and the other part in another country (Canada). Niagara Falls is on the border.

I believe there are actual places where there is a visible line that demarks the two sides. In such locations, if a person were to have one leg one side of the line, and their other leg on the other side, then the person would be considered to be on the border.

In most places, however, no such physical border line exists. So, for most people in most places, the entirety of a person is either in one country or the other. As such they are at the border. This is the used in the same way as when you say that somebody is at the door, or at the gate. That person is standing somewhere with something visibly in front of them.

Alternative prepositions to at are near, nearby, next to, and close to, all of which are actually more appropriate if two things are some distance away from each other.

I have no idea where South Ossetia is, but it sounds to me from the description that it's located entirely within a single country. As such, it should not technically be on the border, but at the border—or, depending on how far away it actually is, one of the alternative prepositions could be more appropriate.

But while that's a literal interpretation of the prepositions, people do still say that a place is on the border, even though that's not literally the case. Figuratively speaking, it's "close enough." So, you wouldn't be faulted for using either on or at—even if South Ossetia belongs entirely to a single country.


At least for physical borders, 'On the border' is generally used for things which are relatively stationary and unlikely to change; towns, countries, houses. You are identifying their fixed location. 'There is a fence on the border between my yard and the neighbor's.'

'At the border' is generally used for things which are mobile and likely to change; migrants, travelers, weather. You are identifying their temporary location. 'The cat is sunning herself at the border between the garden and lawn'.

If I want to use 'on' in a situation that could change, I can emphasize that it is temporary. 'My customs job has me currently working on the border, but I expect a transfer soon.' If I use 'at', I don't need any such qualifications to imply that it is temporary. 'I work at the border.'

Or, I can use 'on' to show that a situation lasted a while, but has since changed. 'I grew up on the border with Canada, but moved away after high school.'

Even when I want to emphasize that something lasted far longer than it should have, using 'at' shows that it was always considered temporary. 'I was at the border for three hours before they let me cross.'

So - do you want to emphasize the nature of the location as being fixed or changing?

"South Ossetia is a small partially recognized country on the Russian South-Western border, and has been since 1991."

"South Ossetia is at the Russian border, but negotiations between Russia and Georgia could soon change this."


Either is acceptable. On the border is probably more idiomatic for a region or town. I would tend to reserve at the border for something that doesn't have an appreciable area, such as a vehicle, building, or person. The dividing line is not very clear, though, and the preference for one over the other is weak in most cases if not all.

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