Run-on Sentences

When two or more sentences (that is, independent clauses) are joined incorrectly within a single sentence, the result is a run-on sentence. There are several types of run-on sentences.

The first type of run-on sentence is missing an appropriate punctuation mark or coordinating conjunction ("and," "but," "for," "or," "nor," "yet," "so") to indicate the independent clauses. It is called a "fused" sentence, as in this example:

As usual, the students are staging a school play this year, one of them also wrote the play.

The second type of run-on sentence uses only a comma to join two independent clauses. This type of error is called a "comma splice," as in this example:

He could not imagine making the same mistake twice, he thought he had learned his lesson the first time.

The third type of run-on sentence consists of multiple independent clauses strung together to the point of becoming awkward and unwieldy, as in this example:

This park has several million visitors a year and sometimes it seems as if they all arrive at once and the rangers wonder whether it would be better to have fewer visitors but they know that people's interest in the park is important and it can help in getting the funds needed to preserve and maintain the park.

Several different approaches can be taken to correcting run-on sentences, and the best approach depends on the intended meaning of the particular sentence. Sometimes separating the independent clauses into more than one sentence may help, as in this example:

As usual, the students are staging a school play. This year, one of the students also wrote the play.

It may be appropriate to add a semicolon to separate the independent clauses, as in this example:

He could not imagine making the same mistake twice; he thought he had learned his lesson the first time.

Yet another possible way to correct a run-on sentence is to add a coordinating conjunction (such as "and," "but," "nor," "or," "for," "yet," "so") to connect the two independent clauses. Unless the sentence is very short, a comma is usually placed before the coordinating conjunction, as in this example:

As usual, the students are staging a school play, but this year, one of them also wrote the play.

In some cases, adding a subordinating conjunction, such as "because," "when," "although," "so," or "if," may help, as in this example:

He could not imagine making the same mistake twice because he thought he had learned his lesson the first time.

Often there are different possible ways to correct a run-on sentence, as in this example:

This park has several million visitors a year, and sometimes it seems as if they all arrive at once. The rangers wonder whether it would be better to have fewer visitors, but they know that people's interest in the parks is important because it helps to get the funds needed to preserve and maintain the park.

With the several million visitors a year to this park sometimes seeming to arrive all at once, the rangers wonder whether it would be better to have fewer visitors. The rangers know, though, that people's interest in the parks is important in helping to get the funds needed to preserve and maintain the park.

To decide among the various possibilities, think about the relationship of the independent clauses to each other (or to one another, if there are more than two). Are all the independent clauses equally important, or are some of them less important than others? Does the logical relationship between the independent clauses need to be clarified?

If the ideas are equal in importance, you may want to keep them as independent clauses. You can either separate them into two sentences or else join them with the correct punctuation and/or coordinating conjunctions.

If they are not equal, or if they have a logical relationship that needs to be better conveyed to the reader, you may want to "subordinate" one or more of the independent clauses—that is, change it into a dependent clause or phrase.