Semicolons

Rule 1

Use a semicolon between two clauses of a compound sentence when they are not joined by a conjunction.  These  sentences must be related in content.

I came; I conquered.
Jake went to the dance; he partied all evening.
Sara bought a new car; she promptly wrecked it.

Rule 2

Use a semicolon between the two clauses of a compound sentence joined by a coordinating conjunction (for, and, nor, but, or, yet, so) if there are other commas in the sentence.  If there is only one extra comma or no possibility of confusion, the comma can be maintained, but it's better to use the semicolon.

The reporters went to Mr. Keely, who was the chairman of the finance committee; and he, in particular, was very cooperative.

Mary, who is my friend, is very stubborn; but her brother, fortunately,  is just the opposite.

Rule 3

Use a semicolon before a conjunctive adverb (moreover, however, nevertheless, then, etc.) and a comma after the conjunctive adverb.

He went home; however, he was very late.
I saw her; then, I got frightened and ran away.
I studied very hard; moreover, I got a good grade.

 

Rule 4

Use a semicolon to separate equal phrases or clauses that contain internal commas.  That is, when there is a list, separate the item itself from the description with a comma, and then separate the items with a semicolon.

Mr. Kuite, a banker; Mrs. Ballard, an office manager; and Mr. Locke, a grocery chain executive, spoke to us yesterday.

He won a million dollars and went shopping.  He bought a car, red and flashy; a boat, big and expensive; and a motorcycle, big and dangerous.

I went with Jane, who is from New York; Susan, who is from Pennsylvania; and Jason, who is from Indiana.