Mecha stuff in the US goes back to Mattel in the mid 1970's where they brought over a ton of different toys under the Shogun Warriors line, everything from Super Sentai to Godzilla was under that brand. But it wasn't until the 1980's did stuff gain significant traction and then later Sentai stuff would re-appear in the 1990's. The stuff in the 1980's is what really spread awareness due to it's popularity. It wasn't the first, but it was the first to have that amount of success. IIRC Voltron was a fuck up and they wanted a different mecha series and were given the wrong one because Voltron had a few toys out in the states prior.
Zoids was another one that went through multiple names and manufacturers in western countries. Robotech itself had a US line in the 1990's under Exosquad. However Robotech toys in the US were under a few different brands like Converters in the 80's. Mind you Harmony Gold bullshit existed in America so that tampered the availability of some of the old veritech figures.
Once transformers hit in 1984 that caused a scramble for anything remotely transforming robot shaped, including stuff that was legally gray and the companies may not have had the proper right towards.
As far as the availability of VHS tapes in the US, that's roughly the same of what they had. I think BIG WARS was another one that was pretty common later on.
Some stuff was just flat out untranslated and I remember there being a sticker that the rental stores would denote that it's not in english.
I mean these are modern numbers but the US market is quite large and always has been. This isn't even getting into stuff like Battle of The Planets which came out a year after Star Wars in America or Speed Racer which predates Star Wars. I'm pretty sure the old releases still call it Japanimation.
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