On our trip to St. Louis over the last two weeks, I found myself wondering whether any other highway has more concurrencies without maintaining its own exit numbers than I-64 does. I count I-64 as having six concurrencies and not maintaining its own exit numbers on five of them:
I-55 concurrency in Missouri and Illinois (together they have no eastbound/northbound exit in Missouri, the westbound/southbound exit in Missouri uses I-64's Exit 40B number, and eastbound/northbound in Illinois they share exit numbers counting up from the state line on their brief concurrency)
I-57 concurrency in Illinois (I-57's numbers prevail, as they also do with the I-70 concurrency further north)
I-75 concurrency in Kentucky (I-75's numbers prevail)
I-77 concurrency in West Virginia (I-77's numbers prevail)
I-81 concurrency in Virginia (I-81's numbers prevail)
I-95 concurrency in Virginia (I-95's numbers prevail)
Is that a record?