I'm was pretty sure the first one came out in 1978, but there's some guy online that says it was 1976.
Mongoose, Redline, Skyway and Jag all started in SoCal. My friend's dad welded for SE Racing, and GT is somewhere in SoCal too. The late 70's/early 80's were a good time to live in SoCal if you were a kid into BMX.