Whew...where to start?
No single book or online reference is going to provide you with much in the way of detailed American history.
Whatever sources you do choose, please remember that historians, like everyone else bring certain biases to the game when they write history so it is very important for you use more than one and try to make sure that the sources are from opposing ends of the political spectrum. Much of what you will read in public school texts is full of PC garbage. Is is important that you use original sources whenever possible and filter that info to glean the clearest picture possible of what REALLY happened way back when.
As I said, no one book will do our history justice. There is just too much time, happenings, people and issues to cover. I tried to remember a few I have read and came up with this list.
Colonial history: Can't remember any off the top of my head but I'd recommend you read about the early settlers in the Massachusettes Bay Colony and Jamestown. Check out sources on the relations between the colonists and the Indians, The French and Indian War, the Tax Acts of 1765, the rise of rebellion and the war of indepence. I would pay special attention to the circumstances surrounding the Declaration of Indepence and later, our Constitution and the first ten amendments, the Bill of Rights. You might want to find out:
-Who wrote these? Why?
-What did the men who wrote the Declaration sacrifice? What happened to them?
-What did the framers of our Constitution really mean when they wrote the document?
-What did THEY see as the relationship between a free man and his "government"?
-What should be the relationship between the federal government and the individual states?
Early American: The papers of Alexis de Tocqueville. As a French noble touring America, his writings are a great window into our early history.
President John Adams: Author David McCullough has a great source for that time period.
Find a good book about Andy Jackson...the first "Frontier President". He broke the chain of men from Massachusettes or Virginia that had held the high office. His administration caused a big stir in government and he brought in major changes to the executive branch.
The Civil War: Shelby Foote...hard to find a better writer and more comprehensive works than his. Lots of stuff there.
Late 19th century and early 20th century: Theodore Rex by Edmund Morris. Great history of President and Congressional Medal of Honor winner Theodore Roosevelt, one of our greatest presidents. Good insight into that gilded age, and the Spanish American War and American expansion beyond our borders. We became a world power then.
World War I: The Guns of August by Barbara Tuchman
World War II: Richard B. Frank's "Guadalcanal" is probably the best ever on the critical campaign that really ended the Japanese expansion and sealed their ultimate fate. Good war read too. This guy knows his stuff.
For Hitler and the war in Europe: The Rise and Fall of the Third Reich by William Shirer. Long...but very detailed on just about every aspect of Hitler and Nazism.
For FDR and Eleanor: Read some of Doris Kearns Goodwin's stuff.
Vietnam and the war: Stanley Karnow. None better.
"The Bomb": Again, I recommend Richard B. Frank. His, "Downfall" is the best book ever written on why we used the bomb on Japan.
The Beat Generation: Jack Kerouac. Good info on the goofy disaffected beats that came of age after WWII and led to my generations hippies.
Again, one text just won't do it. More importantly, whatever sources you do use, read with a certain amount of skepticism. Historians often have agendas that season thier writings.
Good Luck!