1. AP US History This Day in American History September 17
The Constitution of the United States of America is signed by 38 of 41 delegates present at the conclusion of the Constitutional Convention in Philadelphia.

2. AP US History This Day in American History September 17
1862 – Beginning early in the morning, Confederate and Union troops in the Civil War clash near Maryland's Antietam Creek in the bloodiest one-day battle in American history.

3. AP US History This Day in American History September 17
1868 – Early in the morning, a large band of Cheyenne and Sioux stage a surprise attack on Major George A. Forsyth and a volunteer force of 50 frontiersmen in Colorado.

4. AP US History This Day in American History September 17
1976 – NASA publicly unveils its first space shuttle, the Enterprise, during a ceremony in Palmdale, California.