Thanks for your diverse comments

Economically, we were at our strongest after the New Deal was signed and we pulled out of the Great Depression. Those halcyon days lasted for about 40 years (until the 1980's). It's been a downhill slide ever since.

One of the proudest moments in American history was when we landed on the moon...the national pride was beyond belief...we were the most technologically advanced country in the world and we beat the friggin Russians, whom we all hated for unknown reasons (as a child, I had no idea why)...but what made America great was that everyone felt like we were the guardians of freedom, of justice, of equality...we were the good guys that would save people in the world from oppression, poverty, human cruelty...as an American, I felt like I could go anywhere and be proud...to offer a hand, a story...a hope that if you lived in our country, you could be whatever you worked for...people worked hard...they had the American dream of owning a house, a car, having a family, passing on a better world to the kids and grandkids...we helped our neighbors, our community...we were becoming aware of our own prejudices and stereotypes and started looking at the LGBTQ community with new eyes...we saw our failing with our black and brown sisters and brothers...we were working on amends and a move forward...we found our voices in protesting the Vietnam war and in the civil rights riots...we burned our bras and fought for equality for women...it ended when we became complacent...when we stopped being vigilant...when we ignored the increasing gaps in income...when we became greedy and selfish...when we started putting down the young people who would be our future...so now, we have to start all over again...

I think when Al Gore invented the internet

That really depends on one's age or their vision of History. I feel looking back, post WWII was a very good time for America, financially and standing in the world.

It is typical trait of nationalism to call back to a "Golden age" that either never existed at all (The court of Camelot)or a gross inaccurate exaggeration through "Rose Tinted Glasses" of an actual era (Victorian Values and Morality)
Every state in the USA seems to have their own version of this, so a vague statement like
"Make America Great Again" can basically mean whatever the listener wants it to mean, with all those around them agreeing vehemently while having no idea what is actually going on in the other person's head and what they are in agreement with..