The HB has both the BL and the historic route running between I-5 exits 729 and 730 (the BL routing was carried over from CHM). Turns out we were wrong all along, and the north end of the BL and corresponding historic route is actually at exit 732. That is most clearly indicated by signage on southbound I-5, indicating that exit 732 and not exit 730 is the exit to take for both the BL and the historic route. There are also green business Interstate markers on the business route itself north of exit 730.
This isn't a recent development. The AARoads California guide page for the Dunsmuir loops has identified their termini as exits 729 and 732, since 2008. Somehow, none of us figured that out.
I'll update the route file. One technical point is that moving the I-5_N point doesn't work, since people might have ended their northbound travels at exit 730 (which I probably did, until now). My suggested point labels for the I-5 junctions for the BL (whose route file Si can pilfer for the historic route) are:
I-5(729) +I-5_S
I-5(730) +I-5_N
I-5(732)
This avoids breaking list files, while the Updates item would flag that users would need to figure out how much of the BL they actually traveled.
BTW, the AARoads guide suggests that US99Hist continues north on Dunsmuir Ave. past exit 732. I drove that up to exit 734. Plausible that it was once part of US 99, but there's no signage to that effect, and the signage I mentioned above at SB I-5 exit 732 seemingly disagrees.
I'll be shortly leaving California for the last time on this trip, driving north into eastern Oregon as multitudes of eclipse-watchers who descended on Oregon start heading home.
