From 1964 to 1972 was the golden years of muscle cars. All American car makers - or virtually all of their divisions - rushed to produce multiple muscle models to satisfy the hot demand from car enthusiasts.
Ford Mustang - 1964
Pontiac GTO - 1964
Chevrolet Camaro - 1967
Dodge Charger - 1968
Pontiac Firebird - 1970
Then US Muscle Car era ended, caused by safety, fuel efficiency, etc.