A semicolon is used to mark the division of a sentence somewhat more independent than that marked by a comma.
I. Use a semicolon to connect two or more independent clauses.
It is so in war; it is so in economic life; it cannot be otherwise in religion.
Each division of the above sentence could stand independently. Breaking the thought into three sentences would slow it down. Connecting the separate thoughts with semicolons creates a flow and/or sense of urgency.
II. Note that a semicolon may replace the use of a comma and conjunction.
It is so in war, and it is so in economic life, and it cannot be otherwise in religion.
Use either a semicolon OR a comma and a conjunction, but never both together.
III. Use a semicolon before transitional adverbs.
Sarah wanted to buy a Pomeranian; however, her landlord nixed the idea.
Then, however, thus, hence, indeed, accordingly, besides, and therefore are considered adverbs rather than conjunctions, and therefore may be preceded by a semicolon when used to transition from one clause to another.
When the adverbs yet and so are used transitionally as conjunctions, they are preceded by a comma:
It was raining, so I borrowed Ralph's umbrella.
IV. In enumerations use a semicolon between the different links.
The defendant, in justification of his act, pleaded that (i) he was despondent over the loss of his wife; (2) he was out of work; (3) he had had nothing to eat for two days; (4) he was under the influence of liquor.
The membership of the international commission was made up as follows: France, 4; Germany, 5; Great Britain, 1.
Presidents Hadley, of Yale; Eliot, of Harvard; Butler, of Columbia; and Angell, of Michigan.
III. In Scripture references a semicolon is used to separate passages containing chapters.
Gen. 2:3-6, 9, 14; 3:17; chap. 5; 6:15.
VII. Place a semicolon outside of quotation marks.
John's favorite poem is “Ozymandias”; he memorized it to recite to his friends.
The semicolon should be placed outside the quotation marks, unless a part of the quotation.