I came across an old trumpet engraved with "Interlochen made in the USA" on the bell.
I've searched high and low and have not found all that much about them. I did see a few posts that suggested that they *might* be a Martin stencil.
So the one I've got my hands on has a Montgomery Ward Trumpet/Cornet Care card with it. So I'm thinking this horn MIGHT have been sold by Montgomery Ward as some point.
Looking at horn's characteristics, I quickly noticed that the placement and font of the serial number reminded me of my York Airflow. Many of the other features also seem to scream York on them as well. The valve block is numbered in the same fashion. Bottom caps and Finger buttons do looks similar to other York models of the time.
Pull Knob on the 2nd slide is also very close to York's pull knobs of the late 30s, early 40s.
So I'm going to say... (at least the ONE Interlochen Trumpet I've seen) is most likely a York stencil.
Oh and it happen to come with an old York mouthpiece as well (maybe originally sold with the horn... maybe not...)