serious nonfiction for the general reader

Philip Ball, The Modern Myths: Adventures in the Machinery of the Popular Imagination (University of Chicago Press, 2021)
Here's a great work of mythopoeic scholarship, lucid and imaginative. A modern myth, says Ball, is one which originates, or at least is utterly transformed, in modern times with a modern setting. It's not a reconfiguration of older myth like Star Wars or The Lord of the Rings. It becomes myth when it becomes a cultural icon beyond its original literary form, and for that purpose it helps for that origin not to be of too high a literary quality, or else the story will become literature and not a myth, too tied to the original telling.
You can get a sense of what Ball means by his examples, each taking a chapter: Robinson Crusoe, Frankenstein (for the monster), Dr. Jekyll & Mr. Hyde, Dracula, The War of the Worlds (for the alien invasion), Sherlock Holmes, and Batman. A final chapter speculates on the mythic potential of zombies.
Each chapter traces the history of the myth through precursors if any (a lot of them for vampires), details how the author of the core story presented the character, and then how it was transformed in later retellings, especially in movies. And there's also a lot of speculation on what makes these myths gripping. What does it mean that the ultra-rational Holmes was created by an author who fell for hoax fairy photos? Is Mr. Hyde a sexual predator? Is Dracula? Is Batman?
This is all soberly and thoughtfully, not luridly, handled, and Ball doesn't hesitate to evaluate a lot of bad movies or otherwise cast his opinions. (Batman and not Superman, for instance, because Ball thinks Superman is boring.)

Daniel Immerwahr, How to Hide an Empire: A History of the Greater United States (Farrar, Straus & Giroux, 2019)
The author is an academic historian, but this is a general reader's book, not an academic treatise. It's several books in one.
First is a rather fuzzy account of 19C continental expansion, though it goes into guano islands and their contents with great gusto. It's sketchy on the effects on the Indians, and it ignores the long-standing lust for acquiring Canada and brushes off Caribbean filibusters because that would contradict the narrative that the great colony-grabbing of 1898 was an entirely new turn for the US.
At this point the book becomes a history of the Philippines and Puerto Rico as colonies - there's very little on any others; even the guano islands get dropped at this point - but this is the best part of the book, as it tells little-known stories of the US's appalling behavior as a colonial power: the brutal military suppression of the independence movement in the Philippines which our own liberation of them from Spanish rule had fostered; the racist and dehumanizing medical experiments carried out on Puerto Ricans by doctors with reputations as great humanitarians because their sojourns on the island have been brushed out of their biographies. Immerwahr is also pretty caustic on cultural depictions:

West Side Story ... was first conceived as a Romeo-and-Juliet story about a Jewish woman and a Catholic man. But the creative team, seeking relevance, swapped out the Jews for Puerto Ricans. Sondheim was nervous. "I can't do this show," he protested at first. "I've never even known a Puerto Rican." His lyrics bore that out. ...

World War 2 offers an interlude with the only serious considerations of Alaska - the building of the Alaska Highway - and Hawaii. If you've ever wondered why Japanese-Americans were sent to internment camps on the mainland but not in Hawaii, the answer turns out to be that military rule there was so strict as to make the whole islands effectively internment camps.
But after the Philippines win their independence (another strange twist in US policy) and Puerto Rico becomes a commonwealth, the book changes course into soft empire, and here it takes on a strange boosterish quality, as - starting actually with WW2 - American plastics, materiel, mechanical standards (like uniform screw sizes), and the English language take over the world. Immerwahr even credits American empire with the success of the Beatles, for it was a massive nearby US air base that brought American rock & roll records to Liverpool and kicked off the locals' enthusiasm for listening to and making that kind of music. Or so he says. Books on the Beatles usually explain the cultural exchange by pointing out that Liverpool was a cosmopolitan port city. Weirdly, there's little about the harmful effects of these bases. It's blasé about Gitmo and doesn't even discuss Diego Garcia, which you'd think would be red meat for Immerwahr.
So I have my doubts about this book's viewpoint and broad-scale accuracy, but it sure has some interesting things to say.

Sherrod Brown, Desk 88: Eight Progressive Senators Who Changed America (Farrar, Straus & Giroux, 2019)
Democratic Senator from Ohio writes about predecessors who carved their names into the same desk that he uses on the Senate floor. (Apparently this is customary, though there's the occasional puritan who refuses to deface government property.) Some of them are pretty well-known, like Hugo Black, Bobby Kennedy, George McGovern. Others are obscure except to Senate buffs like me. What's curious is that Brown can't hide, and doesn't even try to hide, that two of the least-known, Herbert Lehman and Theodore Francis Green, got a lot more done as governors (of New York and Rhode Island, respectively) than they ever did after coming to the Senate, where they kind of ossified.
The lesson seems to be that yes, you can change America. But only with a heck of a lot of effort and you can't change it very much.