The main question at the end hasn't been answered yet.

I didn't have much space for the title, so here's the real sentence.

The London subway system, which opened in 1863, is the largest, at 394 kilometers, followed by those in Paris and Tokyo, at 199 and 155 kilometers respectively.

As you can see, there are too many commas in this sentence. That's why I asked native speakers yesterday if I could remove any of them, and some told me that the commas before "at" are not necessary and I should add a comma before "respectively". If we removed them, the sentence would have a better flow:

The London subway system, which opened in 1863, is the largest at 394 kilometers, followed by those in Paris and Tokyo at 199 and 155 kilometers, respectively.

So far, I've always thought that we need those commas because the data given is only extra information. Without them, the sentence is still complete.

So, when can we remove this kind of comma?

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    Why do you think there are too many commas? It all makes sense to me. If I did edit the commas I would remove the two before "at", but I would definitely not put a comma before respectively. It's simply an adverb that clarifies the sentence. Commented May 12 at 11:52
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    @PeterKirkpatrick - The AP Style Manual requires authors to include a comma before the word “respectively” at the end of a sentence when making a parallel comparison between multiple items. However, they do not view it as mandatory, considering it a a matter of personal preference, as long as there is consistency throughout the writing. I think this is very much like the case of the Oxford comma. Neither mandatory nor forbidden. Commented May 12 at 12:49
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    @PeterKirkpatrick I think there are too many commas because if each comma is equivalent to a pause, readers have to pause too many times when reading this. Commented May 12 at 14:06
  • @KenAdams - the idea that someone reading aloud must always pause when they reach a comma in writing is misleading. The comma is a punctuation mark for separating distinct information. It helps the reader understand how the ideas in the sentence work together. Although many writers benefit from reading aloud commas as pauses while proofreading, a comma does not always represent a pause in a spoken sentence. Commented May 12 at 14:28
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    I meant choppy in the sense that it's got more than one focal point and is made of relatively short chunks. I could see where you might want to correlate age with the extent of the system and have two things going on at once, but that was not the case, or was the case only with London.
    – TimR
    Commented May 12 at 15:44

1 Answer 1


To streamline the sentence you could do a couple of things:

At 394 kilometers the London subway system is the largest, followed by the Paris and Tokyo subways at 199 and 155 kilometers, respectively.

  • I tried to include "which opened in 1863" in my sentence as it's an important feature I need to report. The London subway was the first system opened in the world. I guess writing a second sentence is an option here. Commented May 12 at 15:20
  • Do you find my sentence "choppy"? Peter and Michael don't seem to think so. If that's true, maybe I don't even have to rewrite my sentence? Commented May 12 at 15:27
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    Since you mention only one opening date, for London, the sentence seemed lopsided and arbitrary. I'd move the opening dates to another sentence where you talk about their relative ages and make this sentence about their relative sizes, thereby streamlining it. I found "those in Paris and Tokyo" clunky. The commas are discretionary.
    – TimR
    Commented May 12 at 15:38
  • Personally I'd omit the comma between kilometers and respectively as well. Commented May 12 at 16:43
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    @KenAdams - To note (maybe?) - New York has the 'Subway', Paris has the 'Métro', London has the 'Underground'. American tourists are regularly confused by 'Subway' signs in London inviting them to descend stairs, but instead of an urban underground railway they find merely a walkway under the adjacent busy road to the other side. Commented May 13 at 8:29

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