Use a Comma
Use a comma to show the omission of a word or words readily understood from context:
In Illinois, there are seventeen such institutions; in Ohio, twenty-two; in Indiana, three.
There is an exception. When, in spite of the omissions, the construction is clear enough without the commas and semicolons, use simpler punctuation (commas only):
One manager comes from UNC, another from Duke, and a third from GW.
Strunk & White Example
Incidentally, superb writers use elliptical expressions all the time. Here are Mr. Strunk and Mr.White, describing the use of that and which, the relative pronouns:
That is the defining, or restrictive pronoun, which the nondefining, or nonrestrictive. . . . Strunk & White, p. 59.