As I walked through the channel — I knew it was over. Is this a correct usage of the em dash?
No. IMO, that sentence requires an ordinary comma.– TrevorDMar 24, 2019 at 23:43
1That -- is two hyphens. This — is an em dash. There is a punctuation guide published by The Oxford Dictionaries, part of which is their Em dash guide.– Weather VaneMar 24, 2019 at 23:46
Usually an em dash signifies an abrupt or drastic change in the direction of a sentence. I don't think this sentence qualifies.The independent clause,"I knew it was over," seems to flow naturally from the dependent clause. "As I walked through the channel." For example, "As I walked through the channel--hell, it's all a lie. There was no channel."– Zan700Mar 25, 2019 at 1:24
No dash and no comma.– Rusty CoreMar 25, 2019 at 15:08
No. You can use a dash to connect two clauses that aren't complete sentences, but in this case where the second clause flows naturally from the first one, you would be better served using a comma. Dashes are usually used to indicate a change in tone or direction (often to a facetious or informal one).
After three weeks on set, the cast was fed up with his direction — or, rather, lack of direction.
If you're using a dash instead of a comma because you feel that a comma wouldn't give the second clause enough weight, you'll probably need to change your wording. Something like this could work:
As I walked through the channel, I realized I had to give up. It was over.