Semicolons and Colons: Getting Coordinated with How to Coordinate Ideas

Written by tutor Colin D.

Semicolons

Definition: A punctuation mark (;) indicating a pause, typically between two main clauses, that is more pronounced than that indicated by a comma.

Proper Uses of the Semicolon

Use a semicolon in a list of terms that already includes commas.

This clarifies compound entities (e.g., city + state) in a list without confusing different subsets of those entities (e.g. city for state, or state for city). For example:

I traveled to a number of cities this summer to visit colleges: Boston, Massachusetts; Eugene, Oregon; Durham; North Carolina; Chicago, Illinois; Madison, Wisconsin; and Albuquerque, New México.

Why not use a comma? The list would become confusing; it would read as though, instead of 6 locations, you visited 12, because the series of commas would not properly differentiate between cities and their states.

For another example, semicolons can also clarify lists of people and titles.

I have taken classes from the following faculty members: Josh Ostergaard, Professor of Mathematics; Fred Smith, Professor of Law; Reginald Champagne, Professor of Political Science; and Jim McGray, Professor of Philosophy.

The list of National League All-Stars included some of my favorite players: Clayton Kershaw, Los Angeles Dodgers; Matt Harvey, Pitcher, New York Mets; Buster Posey, Catcher, San Francisco Giants; and Andrew McCutchen, Outfielder, Pittsburgh Pirates.

Use a semicolon to join two independent clauses with no connecting words.

A semicolon implies the two clauses are related, and perhaps the latter restates the former. For example:

I’ve hiked almost 12 miles today; my throat is dry and my legs are achy.

The meteorologist forecast a temperature of 105° this Saturday; we went camping in the desert anyway.

Improper Uses of the Semicolon

It is improper to use a semicolon before a coordinating conjunction to begin the second independent clause in a sentence. The seven coordinating conjunctions are: And, But, Yet, So, For, Or, Nor.

Example 1:

WRONG: We searched for several hours through city streets and parks; but we could not find our friend’s missing dog.
RIGHT: We searched for several hours through city streets and parks, but we could not find our friend’s missing dog.
ALSO RIGHT: We searched for several hours through city streets and parks; however, we could not find our friend’s missing dog.

Example 2:

WRONG: Our coach told us not to slack off during the summer; and no one on the team shirked even a day of workouts. This sentence uses a semicolon instead of a comma.
RIGHT: Our coach told us not to slack off during the summer, and no one on the team shirked even a day of workouts. Replace the semicolon with a comma to fix the sentence.
ALSO RIGHT: Our coach told us to not slack off during the summer; no one on the team shirked even a day of workouts. You can also drop the coordinating conjunction and use a semicolon.
ALSO RIGHT: Our coach told us to not slack off during the summer; consequently, no one on the team shirked even a day of workouts. You can replace the coordinating conjunction with an independent marker (e.g., a conjunctive adverb).

The semicolon is commonly mistaken for colons and commas.

Colons

Definition: A punctuation mark (:) used after a word to introduce a quotation, an explanation, an example, or a series.

Proper Uses of the Colon

Use a colon after an independent clause when introducing a list. For example:

Upon arriving at the zoo, we saw the following animals: giraffes, elephants, meerkats, toucans, rhinos, and flamingos.

Use a colon after an independent clause when introducing a quotation. For example:

Having endured wild adventures, the wizened and weary Don Quixote laments his knight-errantry: “My mind now is clear, unencumbered by those misty shadows of ignorance that were cast over it by my bitter and continual reading of those hateful books of chivalry.”

Use a colon between two independent clauses to emphasize the second clause. For example:

I cannot fathom why so many people read books online: taking notes is a challenge, and the medium feels less tactile and natural.

The romantic-comedy will always enjoy a wide audience: it tackles the range of human emotion, from highs to lows, from serious to silly.

Use a colon between two independent clauses to define or explain the first clause. For example:

Her poetry was accurately described as funereal: it was dark, brooding, and overwhelmingly melancholic.

Despite a recent series of bad luck, the optimist was irrepressibly ebullient: he was exuberant and cheerful, fully expecting only good luck to ensue.

Improper Uses of the Colon

Do not use a colon to separate independent clauses which neitherr emphasize the second clause nor define or explain the first clause. For example:

WRONG: We went to the hardware store to find supplies to install new lighting in our dining room: however, we left with lighting that would illuminate a whole city.
RIGHT: We went to the hardware store to find supplies to install new lighting in our dining room; however, we left with lighting that would illuminate a whole city.

In this example, the two clauses are related: they both relate to purchasing lights. However, while the second clause does build upon the first clause, it does not define or explain the first. Thus, rather than a colon, a semicolon should be used between the two clauses.

Do not use a colon to separate dependent clauses from independent clauses. For example:

WRONG: Relying too heavily on his parents: Geno failed to develop the skills to be self-sufficient as an adult.
RIGHT: Relying too heavily on his parents, Geno failed to develop the skills to be self-sufficient as an adult.

In this example, the two clauses are related, and the first is a dependent clause whereas the second is an independent clause. In order to connect these two clauses – which together form a complex sentence – you should always use a comma, and certainly not a colon.

The colon is commonly mistaken for the comma and semicolon.