What is the correct punctuation for highway?

"Highway" doesn't require any specific punctuation. It's a noun, and nouns are typically not punctuated unless they are part of a larger sentence or phrase.

For example:

* I drove down the highway. (No punctuation needed)

* The highway was closed due to construction. (No punctuation needed)

* I'm taking Highway 101 to San Francisco. (The number is treated like an adjective and should be capitalized.)

Let me know if you have any other punctuation questions!