This is a very good topic.
I had some knowledge of American history. The oldest layer (and framework) came from elementary and secondary school lessons. In 1400 and 92, Columbus sailed the ocean blue; the Pilgrims landed on Plymouth Rock; One if by land, two if by sea; Jefferson wrote the Declaration of Independence; Lincoln freed the slaves and was assassinated; Teddy Roosevelt; Teapot Dome; FDR; WWII.
Much of what I learned in school was more myth than knowledge. I didn't know that at the time. I thought I was getting the straight dope. In a different sense of the word, dope, I was getting straight dope.
I got by for a long time on myth-history. Myth works, really, as long as one isn't trying to critically examine one's life or one's country or one's world. It wasn't until later adulthood (way way after college) that I began to read material that was more knowledge, less myth, and sometimes not myth at all.
The pieces of mythic history fit together with delusions based on myth, so how can one tell that what we had been given and what we had gathered was not all that true? Was, in fact, bullshit?
It's a process, not an event.
It takes time. First, one hears contrary information -- maybe at a demonstration. Maybe one reads contrary information in a free Newspaper, or a cheap one, anyway, like The Militant, or The Body Politic (gay paper from Toronto) -- NOT the New York Times. Or one goes to a study group. One hears stories on NPR (at least one did in the good old days), or PBS. One sees an eye-opening film like The Fog of War, about Secretary of Defense Robert McNamara who escalated the Vietnam War.
Then one starts seeking out contrary information, and one finds that it too fits together, and decidedly doesn't fit the myths on which one's delusions were based. Noam Chomsky's Manufacturing Consent was a wedge (like a log splitting wedge) that broke open a large hunk of history.
Many books, talks, magazine articles, films, discussions, etc. later, I have a new history that much better accounts for reality. A book on the history of advertising, marketing, and the creation of desires goes a long ways in explaining how I got some of the myths and delusions that are still deep in my memory.
Not only are we deluded, we have been deliberately and elaborately deceived. Somebody will say, "well that just your new myth". No, it fits too many other pieces in too deep a way. So, knowledge about history doesn't necessarily feel good -- I don't like knowing "I drank the Kool Aid willingly".***
***Historical Factoid:
drinking the Kool Aid™ references the mass suicide of the cult led by Jim Jones in Guyana in 1978. It means swallowing all sorts of stuff.
Kool Aid, Kool Aid, tastes great
Wish I had some, Can't wait.
Jingle for Kool Aid.
Kool-Aid is a brand of flavored drink mix owned by Kraft Heinz based in Chicago, Illinois. The powder form was created by Edwin Perkins in 1927 based upon a liquid concentrate called Fruit Smack. Smack is now, at least, another name for heroin; the word is Yiddish, meaning 'sniff' (but not snort). It's a word the Yiddish lists do not eagerly embrace (unlike "schlong").
Tom Wolfe wrote a book, "The Electric Kool Aid Acid Test.
Kool Aid is the official soft drink of Nebraska.
DO NOT DRINK THE KOOL AID!