It's been a while since I took AP U.S. History, and from what I remember it only covered up to WWII. Is this still the case?

I'm not exactly sure what you are looking for, but I have an MA in American Foreign Policy so I can recommend some books on that front.

For a text book type, you could look into The Cambridge History of American Foreign Relations, it is four volumes that covers 1776 to 1991.

If you are looking for a general overview then Walter LaFeber's The American Age is okay. I am torn in recommending this book because LaFeber seems to try and twist the facts into a neat narrative, which is not necessarily supported by the facts. I actually reached out to him to find out his source on something he mentioned about Haitian Revolution, but he couldn't remember exactly where he had seen it. Overall though, the book should be a good jumping off point for further research into an event you want to learn more about.

Ultimately, your best bet is to find a few books on any subject, event, etc. and read them. Don't be afraid to tell your students if you don't know an answer, but make a concerted effort to get them the answer the next day or a son as you can.

I'd take a look at the Oxford History of the United States. So far in the series we have:

The Glorious Cause: The American Revolution, 1763–1789 by Robert Middlekauff, is a mostly political and military history of post Seven Years War America to the ratification of the Constitution. The second edition includes more social history to leaven the traditional narrative, which definitely improves it.

Empire of Liberty: A History of the Early Republic, 1789–1815, by Gordon S. Wood, is a huge tome that covers the period from ratification to the end of the second war with Britain. I haven't gotten all the way through, but I can already tell that Wood is firmly on the side of Jefferson and his Republicans. He sees the Federalists as outmoded elitists, and while his has a point it certainly colors his recounting. Take that into consideration.

What Hath God Wrought: The Transformation of America, 1815–1848, by Daniel Walker Howe, has rather the reverse sympathies. I also haven't finished this one, but it's actually dedicated to John Quincy Adams. It takes a hard look at the xenophobia and genocide that accompanied the expansion of the electorate and responds to Schlesinger's famous Age of Jackson. It highlights the technological innovations that transformed the American economy as European industrialization kicks off.

Battle Cry of Freedom: The Civil War Era, by James McPherson, is probably the best single volume history of the period ever written. If you only read one book on the Civil War, at least read this one. It runs from around 1848 to assassination of Lincoln in 1865.

After that, unfortunately volumes await publication. We pick back up with...

Freedom from Fear: The American People in Depression and War, 1929–1945, by David M. Kennedy. I haven't read this one at all, but I hear good things and the author has a sterling reputation.

Grand Expectations: The United States, 1945–1974, by James T. Patterson, takes a more thematic approach than a chronological one. A strong caveat here (and for the next) would be how little time passed between the events described and its publication in 1997. Historiography marches on.

Restless Giant: The United States from Watergate to Bush v. Gore, also by Patterson, is really only a cursory overview. It was published in 2005 after all. I mention it mostly for the sake of completeness and if you need to brush up on the basic facts from the period.

Finally there's From Colony to Superpower: U.S. Foreign Relations since 1776, by George C. Herring, which I listened to on audiobook. It's a good compliment for the series to have.

I'd just like to caution you against heavily drawing upon Howard Zinn's A People's History of the United States. As [others] (https://www.reddit.com/r/AskHistorians/comments/38slae/what_is_your_opinion_on_howard_zinns_a_peoples/) in this sub have noted, it's revisionist history. I always hated when my high school history teachers fed us agenda-driven history, it just loses its objectivity.

For teaching college surveys of US History, I've used Eric Foner's Give Me Liberty. It's a pretty stock political narrative of American history, but organizes a lot of the conflicts in history around the varying interpretations and ideas of liberty. It's particularly useful for providing context to modern political debates, where one party is generally promoting a brand of extremely individual liberty (except when they aren't) and the other promotes a sense of collective responsibility to build a foundation which people can use to exercise their liberties from (again, except for when they don't).

I would also encourage introducing your students to the idea of historiography - that historians can disagree - and maybe assign a few academic articles or introductions from books that argue something different than your main text's narrative.