About the AP U.S. History Test
This information was collected from the College Board website in 1998 or 1999. Since their new site is more secretive about the details of the test (at least, I can't find this data there anymore), I'm not certain this information is completely up-to-date.
I highly recommend that you check out one of the published books on the AP U.S. History test for more information and sample questions. If you have an additional questions about the test, ask your AP history teacher.