I would argue that there are two kinds of "golden age."
First, you can have a golden age that is golden because a country is better (in one or more ways) than other countries. It can be more powerful in terms of economics or its military or it can be superior in terms of its culture, for example.
Second, a golden age can simply be a time that is better than times before and after in that country (so not in comparison to other countries). It can be a time when the country had it really good in comparison to itself at other times.
I think you can argue that America in the 1950s was a golden age (for most Americans) in both of these ways. The US was the most powerful country in the world both militarily and economically. It was also a time when society within the US was more stable and harmonious than it had been before or has been since. (You can argue that women and non-whites wouldn't see things this way, though.)