The American Microphone Company was one of the early small manufacturers of electro-acoustic devices in the U.S. American Microphone originally was based out of Los Angeles and later moved operations to Pasadena, California. 
I remember growing up in the LA area and attending Los Angeles Unified School District schools that American Microphone was a big supplier of microphones and related equipment for the LA city schools. I spent some time serving on the sound and light crew when I was in high school.
A list of U.S. Microphone manufacturers published in 1937 shows American had over 20 different mikes in production. The list featured several different types of mikes including dynamics, crystals, carbon and condenser models. A popular American carbon type was the model “EL” which sometimes shows up on Ebay.[2A] American’s top-of-the-line dynamic model in 1937 was the D-3. This mike looked very much like the Western Electric 618 and was made under W.E. Patents. This mike had a very excellent frequency response of from 30 to 10,000 hertz within plus or minus 2 db.
After WWII American brought out a very beautiful line of mikes they called “Full Vision” microphones. [3,4,5] These mikes were available in a stunning anodized gold and black finish…the bodies were made of aluminum. The model D33 was also available in a totally black “antihalation” finish that was supposed to prevent a reflection in the TV camera’s lens. The two top models of this line were the omnidirectional dynamic D33 and the multi-pattern model DR330 which was a combination ribbon-dynamic unit with omni, cardioid and bi-directional patterns.[6,7,7A] Both of these mikes delivered excellent quality sound. American also had some less expensive models that used the same case design as the two top units but had lower quality sound. All the “Full Vision” mikes used the standard Cannon XL connector.
In the 1950s LA pioneer TV station, KTLA, used American mikes almost exclusively. KTLA used both the D33 and the DR330 on their many live, local shows. In those days TV directors did not like to see the mikes in the picture so mikes were suspended on overhead booms. KTLA didn’t like to use booms much…so they would hang a D33 or DR330 from it’s cable from a pulley setup overhead. The mike could be lowered or raised as needed.
I remember being in the audience of one of KTLA’s country-western shows in the late 50s when one of the performers hit a hanging D33 and sent it swinging back and forth across the stage! Finally they pulled the mike up on its pulley and stopped the wild swinging…yes, the things that can happen on live TV! Another time in the early 50s I was on a 4-H farm show on KECA-TV [later KABC] at the ABC studios in Hollywood where an American DR330 cardioid was used on the mike boom.
There was also a model D44 omni-dynamic that was specially designed for use in motion picture production. This mike had a special rubber suspension system and an attachment for “fish-pole” type mike booms. The D44 had a very flat, smooth frequency response of 50-15,000 hertz within plus or minus 2.5 db. 
The American Microphone Company was purchased by Elgin Watch Co. somewhere in the 50s and then finally was absorbed by Electro-Voice which continued building the American models for awhile but then finally phased them out completely in the 1960s. A kind of sad end to a very fine U.S. Manufacturer of fine quality microphones and phonograph pickup cartridges.