Well, we discovered that we needed to upgrade security so that potential criminals weren't coming into our country, and so potentially harmful substances weren't being brought onto our planes. That meant literally anything that could become a bomb, start a fire, stab someone etc. As for Pearl Harbour, I think that had more of an affect on how we thought our military and defence system was working.
The Industrial Revolution led Europeans to have better military weapons and this allowed small European armies to defeat larger African and Asian forcer when invading territory. This made possible the colonization of the African continent.
Congress had passed the Civil Rights Act (1964) and the Voting Rights Act (1965) Southern states could no longer deprive African Americans of their equal rights
