Boston and Maine reporting mark.

Hi,
I read online that the Boston and Maine changed its reporting mark from B & M to simply BM in 1938. I could only find one source that stated this. Is this true? Plus, how long after this change did the railroad take to repaint its freight cars. Specifically I am trying to date an old photo which shows in the background what appears to be an old Boston and Maine XM-1 single sheathed boxcar with "B & M" marks, but the road number is obscured. It has the rectangular herald, not the minuteman. Thanks!

Is there anything else in the photo that would provide a clue? Can you show us the image?

Sorry I didn't respond sooner, I was away from home. This picture is from Facebook, comments say Lewiston, Me, Lincoln St., but they disagree on if it is 1930's or 1940's. I am trying to use the railroad car to help date the picture.

I'd say your best bet is to date the automobiles; at least that would give you a "no earlier than" date. I don't know much about autos of that era, but they look early 30s to me, and given they all look like the same vintage...

The newest car or truck in the picture is not later than 1935. They all have fabric roofs; the industry went to steel tops 1936-1937.

PBM

That's a neat photo.
The square herald started appearing on locomotive tenders about 1927. I don't know if freight cars were done before, after, or the same time.
The vehicles in the foreground look bright and shiny. In 1937, manufacturers started putting headlights IN fenders as opposed to on top of them.
I would try to run this photo by the guys on the B&M yahoo group.