Capitalization and Punctuation: Semicolon
A semicolon compounds two independent clauses without a conjunction.
Come with me; you'll be glad you did.
A semicolon compounds two independent clauses where the second clause begins with a transitional expression.
In the sentences below, furthermore and however are transitional expressions.
There must be something I can do; I've been sitting here for an hour.
I'll show you the sights of my childhood; furthermore, we'll visit the alley where I learned to skate.
Notice that a comma follows the transitional expression in the sentences above.
I thought we'd said enough about that; however, the look on your face tells me that you have something more to say.
For more on transitional expressions (also known as adverbial conjuctions), see the section on Avoiding Run-on Sentences and the section in Chapter 16 on Transitional Expressions.
A semicolon separates items in a series when the items already contain commas.
As program director, she had several responsibilities: planning, budgeting, contracting, and hiring staff for the summer projects; managing the projects and supervising the staff; and at the end of the summer, closing the offices, distributing remaining funds to agency departments, and writing final reports.