In Pennsylvania one drives "30" or "22", never with "the" and seldom even prefixing "route" or "US".
Texas just says "35".
[0]: https://www.pbssocal.org/shows/lost-la/the-5-the-101-the-405...
Socal retained the names for freeways much longer than the usage in the north (the bayshore freeway was assigned 101, while, say, 280 or 17 never had names AFAIK). pilingual (does this mean they speak English, Spanish, French, and Southern Californian?) linked to an article that describes this phenomenon in the south.
Native Californians code switch based on location.
Some Socal history:
How Los Angeles got in the habit of putting ‘the’ in front of every freeway name
https://la.curbed.com/2017/9/6/16264074/socal-los-angeles-th...
Northern California doesn’t use the “the” for example.
Back in IL nobody did this, at least not when I lived there over a decade ago.
A notable exception is Lake Shore Drive (US Highway 41) which everyone just calls “Lakeshore” in conversation with no article.
I grew up out in the west suburbs, everyone just said "88" "53" "59" "355" "i80" etc.
The economy of two syllables instead of three wins I guess.
I had one professor who was an unironic “fardy” speaker. I think it’s not common under 50 anymore. But I also haven’t been in town for a long time.
However dropping the classification from a number is equally problematic be it the timezone (E.G. EST / New York) or a freeway.
Absent even any other context, MOST Americans would probably at least consider a highway / freeway / other major vehicle route in their head hearing I-(number).
Also, you can’t authoritatively say “the X” because of the multistate nature of the metropolitan area, where talking about “Route 17” may refer to either NY 17 or NJ 17.