I think this mix up, another one that’s not a classic troublesome pair, in that one is correct and one is incorrect, comes from people writing down what they think they’ve heard. This has come up with Here! Here! vs. Hear! Hear! and would of vs. would have, too. I’ve started noticing this one a lot on Twitter, too, so it might be that people just stick down what they think it might be when typing in a hurry.
Incorrect: on route. Correct: en route
The incorrect usage does make sense in a funny kind of way, and it sounds the same too, but, it really isn’t!
So, as we probably know, it means “on the way” to or from somewhere. It comes from the French – 18th Century French, so it’s been around for long enough that it’s stuck and isn’t likely to be that pliable. You can use on route, but only in a very specific sense, when talking about named roads in places like America. And then there’ll be a capital in the middle, and you’re not using it in precisely the same way. So, “On Route 66 I found a lovely motel” – fine. But in all other cases: “I was en route to Chicago when I happened upon a charming hotel” – also fine.
This also applies to phrases like en masse. If there’s an “on” sound and the other word looks like it might be French, check it!
You can find more troublesome pairs here and the index to them all so far is here.
LibroEditing proofreading, editing, transcription, localisation 
Linda
January 8, 2012 at 12:35 pm
I saw ‘on masse’ and ‘on mass’ in an online conversation the other day. Soon we’ll see hotels advertising their ‘on sweet’ rooms….
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Liz at Libro
January 8, 2012 at 12:39 pm
Oh no – it’s crept over from on route!
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William
June 8, 2012 at 12:54 pm
This is always a mistake I hated but just now spotted this sentence in my edition of Thomas Pynchon’s ‘The Crying of Lot 49’:
‘She had decided on route, with time to think about the day preceding, to go see Dr Hilarius her shrink, and tell him all.’ (91)
I’d be interested if anyone had an alternative edition (mine is Vintage, 1996) to see if this is a misprint or a misuse?
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William
June 8, 2012 at 12:57 pm
Apologies for that first sentence…!
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Liz at Libro
June 8, 2012 at 1:06 pm
No problem – I don’t go over my comments with my red pen or anything!
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Liz at Libro
June 8, 2012 at 1:05 pm
Oh dear: it’s always bad when you spot a particular bugbear in something published!
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Katherine
July 17, 2012 at 9:46 pm
Brilliant, I’ve been following your blog for a while, and when searching for a definitive answer on this question, this was the top search result on Google!
And also, phew, I knew ‘on route’ just looked strange.
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Liz at Libro
July 17, 2012 at 10:09 pm
Thank you for the vote of confidence. It’s been top result on Google for a while now and I guess that emphasises its own effect or something. It’s my most popular blog post now! Glad I could help, anyway!
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Jason
December 18, 2012 at 9:57 pm
Bravo! Thanks for posting this. I love proving my coworkers wrong. 😉
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Liz at Libro
December 19, 2012 at 8:11 am
You’re welcome! This is my most viewed post ever in the history of my blog!
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Ann Cooper
March 5, 2013 at 5:33 pm
Thank you for this. Whenever I see a “Baby on route” sign in the back of a car, I want to tell them to take the baby off the route because chances are, someone will run it over!
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Paul Mead
June 21, 2013 at 12:12 pm
I’m loving the “on sweet” rooms comment.
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Not French
March 9, 2014 at 7:07 pm
We English speaking people could stop using the French phrase and translate it into English “in route”.
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Liz at Libro
March 9, 2014 at 7:09 pm
“On the way” works pretty well …
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Yet Another Geek
August 28, 2014 at 1:36 pm
Sorry, but this is a non sequitur.
You have identified that ‘en route’ is an established and acceptable borrowing into English. Fair enough.
But there is no basis for using that to declare that ‘on route’ is incorrect. ‘En’ means ‘on’ and ‘route’ means ‘route’. The fact that you can substitute ‘on the way’ just underlines this.
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Liz at Libro
August 28, 2014 at 1:42 pm
Thank you for your comment. I would note that “on route” is not a phrase used in standard (UK) English – “on the route” maybe, like “on the way” but it needs the “the” to make sense. Hence “en route” is correct, “on the route” is correct, “on the way” is better if you don’t want to use the borrowing, and “on route” isn’t correct. I also firmly believe that this is one of the very common mishearings (see “would of” vs. “would’ve” for another example), and people don’t realise that they should be writing “en route”, because they’ve heard “on route”.
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Nick S
April 28, 2016 at 3:13 pm
The “en” when used as a preposition in French does not only mean “on”, it also has a conditional or transformative connotation, among others. E.g. “être en bonne santé – to be in good health” or ”
être en guerre – to be at war”.
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Yet Another Geek
August 29, 2014 at 3:12 pm
Now you are disguising the non sequitur with a formal fallacy.
1) You assert that X and Y are mutually exclusive.
2) You write a big chunky paragraph showing the correctness of X.
3) Right in the middle of this you embed “Hence….. Y isn’t correct”.
5) “Hence” (like ‘therefore’) is indeed used to mark deductions but just repeating your original assertion with the word ‘hence’ in front of it does not make it a deduction.
Conclusion
‘On route’ is grammatically correct, meaningful and unambiguous English.
BTW
I go to work, I but my ticket on departure and I take my coat off on arrival. I do not go to the work, I but my ticket on the departure and I take my coat off on the arrival. I leave the ‘the’ at the home.
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Liz at Libro
August 29, 2014 at 3:40 pm
OK, so in my opinion, and in my editing practice, I understand en route to be correct and on route to be incorrect. I’ve laid out my reasons why. The glory and nightmare of English is that there is more than one answer to many questions. I stand by my guidance and respect your opinion and decision on the matter; that’s all one can do in this kind of case!
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E Rekstein
February 27, 2015 at 11:58 pm
Wow. I’m finding “on route” useful and “en route” awkward. But since I don’t want my readers to stumble over “on route”, likely I will find another way to state my point. I’m a stickler for grammar but “on route” doesn’t seem to violate anything, in my opinion.
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Liz Dexter
February 28, 2015 at 5:54 pm
Thanks for your comment – it’s a French phrase, and the French phrase doesn’t use “on”. It’s fine to say “on the route” to somewhere, of course, but that doesn’t get across the precise meaning.
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Rachel Brown
September 8, 2015 at 12:51 pm
Do you think using ‘On Route’ as a name in regards to a travel blog would be detrimental? Im looking to start one and liked the ring of Rachel On Route – but I was concerned as its not technically correct. I’m not super keen on using the proper French ‘En Route’ because I am neither French or travelling to France any time soon, and was worried it would give it a French dynamic which Im not looking for. But I really like the name. Do you think it would annoy people enough to be put off reading the blog, or is it an offense that can be over looked (as long as the content is good of course 😀 ) Thanks, Rachel.
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Liz Dexter
September 13, 2015 at 6:49 pm
Hm, I would say it would put off a certain number of people … and they might well talk about it, too. Could you use “on the route” as an alternative? Or Rachel on the road?
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Nick S
April 28, 2016 at 3:33 pm
“on the way” would be the correct English translation of “en route” since both are figurative expressions that can express being in a state of travel by various means.
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