Almost all serious engineering, scientific [..] and the majority of manufacturing are metric in the U.S.
This isn't true in my experience. Of course my experience certainly isn't comprehensive, but in my work I interact with a lot of US fields (environmental, manufacturing, civil & mechanical engineering, etc) and I almost never see metric units. The Federal Highway Administration tried to encourage state DOT's to go metric for design and engineering work back in the late 90's but they eventually gave up. If you ever worked on an American car, you still find a mix of metric and Imperial bolt sizes! About the only field where I found that metric units are used extensively is wind energy.
Heck, even my mechanical engineering PE exam used Imperial units exclusively (pounds force vs pounds-mass... sigh)
I imagine that your statement is probably most true for the military though.
This isn't true in my experience. Of course my experience certainly isn't comprehensive, but in my work I interact with a lot of US fields (environmental, manufacturing, civil & mechanical engineering, etc) and I almost never see metric units. The Federal Highway Administration tried to encourage state DOT's to go metric for design and engineering work back in the late 90's but they eventually gave up. If you ever worked on an American car, you still find a mix of metric and Imperial bolt sizes! About the only field where I found that metric units are used extensively is wind energy.
Heck, even my mechanical engineering PE exam used Imperial units exclusively (pounds force vs pounds-mass... sigh)
I imagine that your statement is probably most true for the military though.