Is the em dash used in formal writing?

Question

Is it valid to use em dashes in formal writing? My teacher said it's informal to use em dashes under any circumstances, so I just wanted to make sure. I've gone through several related questions in here but there is no direct answer. This was my sentence: 'In fact, as shown in latest statistics, 12.5% of America’s citizens are African Americans—who most of them are descendants of enslaved people—and they are all treated equally.' It was in a paragraph about slavery.

Answer 1

First of all, I would advise you to rephrase as "of whom most are descendants of enslaved people".

As to your question about dashes, punctuation rules vary depending on what style manual you are expected to follow. In this case, it sounds like your teacher has their own style they require their students to use, so that will always be your determining factor. After all, they're the one grading your work. If the teacher says no em dashes, just don't use them and make your life easier.

There is no single "formal" style of writing. It sounds like you are in high school, but when you get to college writing you will be expected to follow a standard style manual which is available as a book or searchable online style guide. English classes will generally be told to use MLA style (https://www.mla.org/MLA-Style), for example. You can easily google "MLA style xxx" about whatever grammar, style, or punctuation questions you have while editing your homework. If your teacher still disagrees, at least you can say you followed a credible resource. Good luck!

Answer 2

Hello! The em dash is, indeed, a little more casual and should usually be avoided in academic writing (though, there are always exceptions). In most cases, you can probably use commas instead of em dashes. One of the purposes of commas is to separate nonessential information from essential information in a sentence. If you can remove that part and the sentence still makes sense, then it likely needs to go in commas. I would recommend one additional grammar correction for your sentence:

1. In fact, as shown in latest statistics, 12.5% of America’s citizens are African Americans, most of whom are descendants of enslaved people, and they are all treated equally.

"Who most of them" is a little wordy and awkward, as it uses both a subject pronoun and an object pronoun to refer to the same people. "Most of whom" is the more commonly used phrase in this case.