Writing Essentials
9 Run-on Sentences
Another common error in student writing is the run-on sentence.
The basics
Just as short, incomplete sentences can be problematic, lengthy sentences can be problematic, too.
As writers, we want to ensure our sentences always form a complete idea to avoid confusion for our reader. A “complete sentence” is also known as an independent clause, which we learned about in the previous chapter. Here’s an example:
Both sentences are independent clauses. They both express a complete idea.
However, many people make mistakes when they incorrectly combine two or more independent clauses. This is what is known as a run-on sentence.
A run-on sentence can take two main forms. Read the examples below and see if you can identify what is wrong with each.
Example #2: I have to complete my project by tomorrow, it is worth 30% of my grade.
Example #1 is known as a fused sentence. This means that two independent clauses are combined without any punctuation.
Example #2 is known as comma splice. This means that two independent clauses are incorrectly joined by a comma.
Look at two more examples below. Can you tell which one is a fused sentence and which is a comma splice?
Example #1: We looked outside, the kids were hopping on the trampoline.
Example #2: A family of foxes lived under our shed young foxes play all over the yard.
Example #1 is a comma splice. Example #2 is a fused sentence. Let’s do some more practice identifying the two.
Fixes for run-on sentences
While run-on sentences are extremely common, they are also easily fixed by using punctuation, coordinating conjunctions, or subordinate conjunctions.
Punctuation
A period and a semicolon are the most common punctuation marks used to fix run-on sentences.
A period will correct the error by creating two separate sentences.
Run-on: There were no seats left, we had to stand in the back.
Complete Sentence: There were no seats left. We had to stand in the back.
Using a semicolon between the two complete sentences will also correct the error. A semicolon allows you to keep two closely related ideas together in one sentence. When you punctuate with a semicolon, make sure that both parts of the sentence are independent clauses.
Run-on: The accident closed both lanes of traffic we waited an hour for the wreckage to be cleared.
Complete Sentence: The accident closed both lanes of traffic; we waited an hour for the wreckage to be cleared.
Make sure that both ideas are closely related before you use a semicolon. If they are not related, you should not use a semicolon.
For example, a semicolon shouldn’t be used in the following sentence because both ideas are not related:
Now, you might be saying, “What if they ate fast food because of the accident? Wouldn’t the two sentences be related then?”
In such a case, you may be right. But it falls on the writer to make that distinction clear to the reader. It’s your job to make sure the connection between your ideas is clear. This can be done with transition words.
When you use a semicolon to separate two independent clauses, you may wish to add a transition word to show the connection between the two thoughts.
After the semicolon, add the transition word and follow it with a comma:
Run-on: The project was put on hold we didn’t have time to slow down, so we kept working.
Complete Sentence: The project was put on hold; however, we didn’t have time to slow down, so we kept working.
We can also apply this to our incorrect example above:
Incorrect Semicolon Use: The accident closed both lanes of traffic; we ate fast food for dinner.
Correct Semicolon Use: The accident closed both lanes of traffic; therefore, we ate fast food for dinner.
Coordinating conjunctions
You can also fix run-on sentences by adding a comma and a coordinating conjunction.
Remember, a coordinating conjunction acts as a link between two clauses.
Use these words appropriately when you want to link the two independent clauses.
Run-on: The new printer was installed, no one knew how to use it.
Complete Sentence: The new printer was installed, but no one knew how to use it.
Subordinate conjunctions
Adding subordinate conjunctions is another way to link independent clauses. As with coordinating conjunctions, subordinate conjunctions show a relationship between two independent clauses. There are many different subordinate conjunctions. Check out this link to see a list.
Run-on: We took the elevator, the others still got there before us.
Complete Sentence: Although we took the elevator, the others got there before us.
In the example above, the run-on is a comma splice, which results from joining two complete ideas with a comma. In the correct example, the subordinating conjunction “although” appears at the start to show the relationship between the sentences. Now it’s okay to combine both sentences with a comma.
Here’s another example:
Run-on: Cobwebs covered the furniture the room hadn’t been used in years.
Complete sentence: Cobwebs covered the furniture because the room hadn’t been used in years.
In this example, the run-on is a fused sentence. We fixed this issue by inserting the subordinate conjunction “because” in between both sentences.
Key Takeaways
- A run-on sentence occurs when two or more independent clauses are connected without proper punctuation.
- There are two types of run-on sentences: a fused sentence and a comma splice.
- A fused sentence occurs when two independent clauses are combined without punctuation.
- A comma splice occurs when two independent clauses are combined with a comma.
- Both types of run-on sentences can be fixed by adding correct punctuation, a coordinating conjunction, or a subordinate conjunction to the sentence. The one that’s best depends on the information the writer is trying to convey.
References
Possel, H. (n.d.). Transition Words. Smart Words. https://www.smart-words.org/linking-words/transition-words.html
Traffis, C. (2020, December 16). What is a subordinating conjunction? Grammarly. https://www.grammarly.com/blog/subordinating-conjunctions/
Attributions
This chapter was adapted from Effective Professional Communication: A Rhetorical Approach by Rebekah Bennetch, Corey Owen, and Zachary Keesey, which is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
Bennetch, Owen, and Keesey adapted their chapter from “Communication at Work” by Jordan Smith (on Open Library). It is licensed under Creative Commons Attribution 4.0 International License.
Bennetch, Owen, and Keesey also adapted their chapter from “Writing for Success” by University of Minnesota (on University of Minnesota Libraries Publishing). It is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License
a clause that can stand on it's own because it conveys a complete idea.
a writing error where two or more independent clauses are connected without proper punctuation
when two independent clauses are combined without any punctuation
when two independent clauses are incorrectly joined by a comma
a word that joins two clauses, such as "and," "but," "for," "yet," "nor," "or," and "so"
a word that connects a dependent clause to an independent clause. It shows a cause-and-effect relationship or a shift in time and place between the two clauses
words that are used to connect words, phrases, or sentences. Examples include: as a matter of fact, moreover, in other words, and as a result
