# semicolon vs conjunction "and"?

Does using a semicolon to join two clauses form a coordinate construction with two clauses coordinated and is it the same as with "and" and are such sentences interchangeable ? And can we omit words(ellipsis/gapping) as we did with coordinate structure ?

In 2000 there were seven cases; in 1999, five.
In 2000 there were seven cases and in 1999, five.

In 2000 there were seven cases; in 1999, five.

Yes, this can be considered coordination. Specifically, it's asyndetic coordination, meaning that there is no overt coordinator such as and present.

Yes, both of your examples have the same meaning. As you suggest, the first sentence is an example of gapping with the existential there were omitted from the second coordinate:

In 2000 there were seven cases; in 1999, there were five cases.

We can find a similar example in The Cambridge Grammar of the English Language, p.1744:

Some of the immigrants went to small farms in the Midwest; others, to large Eastern cities.

This is explicitly labeled as an example of asyndetic coordination with gapping and a semicolon.

In most but not all cases gapping is equivalent to a non-gapped version:

In 2000 there were seven cases; in 1999, there were five cases.
In 2000 there were seven cases; in 1999, there were five cases.

These examples are interchangeable.

The rule I know of is summed up as:

"a semicolon should be used to separate two independent clauses (or complete sentences) that are closely related in meaning."

Technically, "In 1999, five" cannot stand as a complete sentence. "In 1999, there were five cases" can. You can also build a sentence diagram for "In 1999, there were five" (although it makes me a bit uneasy standing alone).

But in practice your first sentence wouldn't be misunderstood. That pattern is used frequently. It's most often qualified somehow to show the point you are trying to make with the contrast. Dramatic pauses are usually used when spoken:

In 2000 there were seven cases; {...beat...} in 1999, {...beat...} only five.

British journalists would say it exactly like this, and you would write it down using a semicolon.

Putting the "and" in doesn't have correct grammar, yet doesn't offer the same leeway. Perhaps because the spoken form is awkward: if you put `and` after the beat you've waited too long, while if you put it before the beat it leaves people hanging in an awkward way.

In 2000 there were seven cases and in 1999, five.

...so that form should be avoided.

• Separating independent clauses is not the only use of the semicolon. They are also validly used as list item delimiters when the item content contains commas, and when making parallel statements and ellipting repeated content, as done in the question. In both cases, they serve to show the boundaries between statements or items. The stronger separation provided by a semicolon eliminates potential ambiguity (either when speaking or writing). Commented Sep 11, 2014 at 6:12