Enjoyed. From SPUI: "1-28-38-2 must have been from when you could turn left on mass ave from mem drive". There are definitely some historical lessons to be learned from this about roads in Boston - a lot we don't know (like why is the 2 reversed but not the 28/38?).
I had thought that 1/28/38 crossed the Tobin and headed into Somerville that way. What routing would it take if it went down Mem Drive? The guide signs for 1/28/38 to downtown Boston imply that 1/28/38 crossed elsewhere than 2, so if 2 took the Harvard Bridge, then what did 1/28/38 take?
as for the shields:
the 28 and 38 are actually an earlier spec (1948 or 1949), while the 2 is an experiment they did around 1952 to see if the black shields reflect better. The US-1 must also be from that experiment, though they must've given up on it because I've seen a US-5 from 1955 that is the standard colors, and also the state route markers reverted sometime around then too. Here is the 1955 US-5:
www.aaroads.com/shields/show.php?image=MA19550051t200050.jpg&search=5the really inexplicable thing? Why did they use the Mass custom font for everything except that run of inverse-striped state shields?? Both before and after; in general they didn't use the MUTCD font until the mid-1970s.
a small aside: that custom font has been around since 1931 or earlier, as these photos are from 1931:
www.aaroads.com/shields/show.php?image=MA19300011t200010.jpg&search=1note the guide sign with the custom fonts - also note the cast aluminum "State Highway Begins Here", which can still be found to this day.
Massachusetts did a lot of weird things. Here is a font that much resembles the MUTCD 5, on a 1939 shield:
www.aaroads.com/shields/show.php?image=MA19390051t200050.jpg&search=5(I have seen that "5" on a catalog from 1935 that shows some Connecticut guide signs, so it's not like the idea for making a "5" that looked like that came springing anew in 1943 when Highway Gothic was invented, but still interesting to see it in 1939 in field use)