When is it correct to use a semicolon before a list or quotation (if at all)?

Solution 1:

All else being equal, the two uses of the semicolon that you've listed are incorrect.

Thus:

INCORRECT: John said of the event; "It's great to see everyone."

CORRECT: John said of the event, "It's great to see everyone."

CORRECT BUT DIFFERENT: John enjoyed the event; "It's great to see everyone," he said.

The last example proves that you can have a semicolon immediately before a quotation, but (a) this is rare construction and (b) it's structurally different from the actual example, which is why it works.

As for your other instance (using a semicolon to introduce a list, instead of a colon), allow me to invent a sample sentence:

INCORRECT: I bought three things; apples, bananas, and carrots.

CORRECT: I bought three things: apples, bananas, and carrots.

CORRECT BUT DIFFERENT: I bought three things; apples, bananas, and carrots are all tasty.

The final sentence is structurally different (the words after the semicolon form an independent clause), which is why it works.

Note: Since the question was about whether it's ever OK to use a semicolon in place of a colon in these situations, I haven't gone into the details about semicolon use in general or colon use in general, but if you want a refresher, there are great details at the following pages:

Stack Exchange links:

• Semicolon versus dash
• Using a semicolon correctly
• Full stop versus semicolon

External links:

• Using semicolons (University of Wisconsin Writing Center)
• Semicolons, colons, and dashes (UNC-Chapel Hill Writing Center)