When people say they want to "Make America Great Again", mainly Trump supporters, what does it mean? What time in American history is being hearkened back to that the current America is somehow inferior to?
You may ask what "time" or "time period", but there is no "time" or "time period" that's really being referenced here by such speaker(s).
It's simply a
condition the speaker(s) are referencing or even merely maybe somewhat imagining.
When speaker(s) allude to "making America Great
again" they're wanting a condition created/restored.
That condition is usually a situation in which the speaker(s) would experience life being better for them than it is now.
Not everyone would agree that under certain conditions referenced by the speaker(s) America would really be "great".
But the speaker(s) think it would be.
For Trump supporters, it's usually that "foreign-looking" anything wouldn't be "favored" or "favored over" the more "traditional-looking", and such a condition once existed in America, some say before the 1960s, others say before the 1930s, etc..
For Sanders supporters it's usually that "rich" anything wouldn't be "favored" or "favored over" the current money-hierarchy "losers", and such a condition never really existed all that greatly, so this speaking would be an imagined condition.