It was the Articles of Confederation that formed a loose union of American states in this way. These Articles were too weak to truly unite the nation, however, and were therefore replaced by the Constitution.
The threat of terrorism has grown significantly. Although there were terrorist strikes before to 9/11 (e.g., the bombing of embassies and the bombing of Oklahoma City), none were as serious or well-planned.
increased security at airports and on aircraft. The entire globe wished to avoid another 9/11.
War in Afghanistan: After 9/11, America developed a mistrust of the Taliban-led Afghanistan and the fact that it was harboring several terrorist organizations.
War in Iraq: Following 9/11, there were concerns that Saddam Hussein was harboring terrorist organizations that aimed to harm the US and the West as well as being suspected of possessing WMDs. All of this culminated in the Iraq War in 2003, the effects of which are still being felt today (ISIS)
distrust of the Muslim community. Americans had a great deal of mistrust towards Muslims in general after 9/11 because they thought some of them would be terrorists. This mistrust is still present in the alt-right movement today.
Patriot Act: broad citizen surveillance to combat terrorism (lone wolf or part of a group). This conduct sparked a heated discussion about the trade-off between freedom and security, which continues today.
The American endeavor to police the world did not end in Iraq and Afghanistan. Additionally, there were military operations in Somalia, airstrikes in Libya, and support for Syrian rebels.
