Is the group of words in bold a phrase or a clause?
President Lincoln’s Gettysburg Address, one of the most significant speeches in
American history, contained under three hundred words and lasted only two minutes.

The group of words in bold, “President Lincoln’s Gettysburg Address, one of the most significant speeches in American history,” functions as a noun phrase. Noun phrases can include the main noun along with modifiers that provide more information, such as adjectives and prepositional phrases, which is exactly what we see here!

When evaluating whether something is a phrase or a clause, remember that clauses contain both a subject and a verb. Phrases, on the other hand, are simply groups of words that act as a single unit without a complete subject-verb set. In your example, there’s no verb present in the bolded text, solidifying its status as a phrase!