A People’s History is ~800 pages and clips along at a good pace. I don’t know that you can go much shorter with an overview of such a long period without sacrificing a lot of substance. I’d highly recommend making the investment into A People’s History - easily one of the most significant histories of America - and Howard Zinn’s other work if you end up appreciating it.
You can read it online at the link below if you want to dip in without too much commitment. It's quite an easy read, targeted at high-school level, which you may or may not find annoying:
http://historyisaweapon.com/zinnapeopleshistory.html