The big thing I've noticed in all these discussions is that because education is handled locally, there's a pretty wide array of experiences. It'd be interesting to have everyone post what their schools covered, and compare notes.
I lived in a liberal enclave with a very highly rated school system, so we covered a bunch of the stuff that people say got left out in their schools: slavery, Jim Crow, Japanese internment, the trail of tears, the Gilded Age, etc.
Anyway...
4th Grade: Local history. Lord Baltimore, etc.
5th: Lots of stuff on Native Americans, and some Oregon Trail type activities.
6th: Greeks and Egyptians.
7th-8th: Native Americans, The Sun He Dies, some Medieval & Renaissance European, some Asian, immigrant experience in the US. It's all fuzzy before HS, can you tell?
9th: American History. Starts just before Columbus, goes through WW1 or WW2. Focuses on the political/social movements over particular incidents and date/place factoids. Revolutionary War, Federalists vs. Republicans, Era of Good Feelings, Whigs then Democrats, Civil War, Reconstruction, Progressive and Populist Movements, etc.
10th: NSL Gov't. First semester was how government works, second semester was basically modern US history. Cold War and all that. Teacher was basically cruising until retirement, so pretty fuzzy.
11th: World History. First semester was just random factoids all over the map covering over a millenium. Cradle of civilization! Medieval Europe! West African empires! China's dynastic cycle! Aztecs and Mayans! The French Revolution! Very confusing. Second semester was mostly the World Wars, and more coherent.
Looking back, there's a lot of repetition between elementary and HS, but that makes sense. How much are you really going to absorb when you're 9?
One thing I'd overhaul is world history. We got half a year in HS that covered this century, and it did very little to make sense of what's happening now. The US history was actually very good, and put things in context.