Gotcha. Didn’t realize that toll freeways could not become toll interstates.
Yeah... I don't think that statement is really true. As others mentioned, there were a bunch of "grandfather" type situations, but there also have been recent additions of toll roads as interstates.
Of course, they have the rules against tolling an interstate that was built as a free road (there's a lot of experience in PA here with I-80) - or any free road (it doesn't have to be an interstate).... Does it
really work the other way around too?
I'm guessing that building an interstate-standard toll road doesn't guarantee it would get approved for an interstate number if requested - but I don't think it's blatantly not allows.
I'm wondering if new non-interstate toll roads (like the ICC) are sticking with State Route number is because the agency doesn't care enough to pursue and interstate designation.