I noticed recently that USGS topo maps on Acme Mapper show two sets of sequential numbers for I-93 in Massachusetts - and neither one matches the sequential numbers that existed up until the mile-based exit numbers went in a couple of years back. This is most obvious
here, where the Ballardvale exit (now Exit 38) is split between two quadrangles of different vintages. In one vintage, it's Exit 16, on a system that seems to start with Exit 1 in Charlestown. In the other vintage, it's Exit 30, in the "Route 128 = Exit 25" scheme that was used on a couple of other highways in the past. Up until a couple of years ago, it was then Exit 42, and now it's Exit 38.
So, I-93 north of Boston has had four sets of exit numbers:
Scheme -> | A | B | C | D |
MA 16 | 5 | 19? | 31 | 22 |
MA 128/I-95 | 11 | 25 | 37 | 28 |
I-495 | 18 | 32 | 44 | 40 |
where Schemes A and B were described above, C was the pre-2021 sequential numbers, and D is present-day.
First off - is there a site anywhere that lists the history of exit numbers on various Massachusetts highways? I swear that I once read something about the "Exit 25 = Route 128" scheme but I can't seem to find it anywhere now.
Are there any other highways that have had four sets of exit numbers at various times? I can't think of any. There are some that have had three:
- MA 3 - the "Exit 25 = Route 128" scheme (25 at I-93/128 -> 42 at Cedarville), pre-2021 sequential numbers (1 at US 6 -> 20 at I-93), present-day mile-based (1 at US 6 -> 43 at I-93)
- MA 25 - pre-2007 (exits 1 & 2), 2007-2020 (exits 2 & 3, to avoid confusion with I-495's Exit 1), and 2020-present (mile-based, Exits 3 & 10)
- The MA 128 portion of I-95 - MA 128's numbers (30 at US 1 Peabody -> 63 at I-95 Canton), I-95's sequential numbers (26 in Canton -> 44 in Peabody), mile-based (26 in Canton -> 63 in Peabody)
A couple of other questions for the historians/old map collectors in the forum:
- Did I-290 ever have sequential exit numbers for the period before MA 52/I-395 was completed, starting with Exit 1 at I-90, or was it numbered starting with Exit 7 right from the start to anticipate merging with 395's exit numbers?
- Did I-495 ever have exit numbers starting with 1 at the southern I-95 junction in Mansfield, before it was extended further southeast?
- Did MA 25 ever have different exit numbers beginning at the original west end at MA 24, before it was mostly redesignated as I-495?