Okay I only know 2 things: The sinking of the Lusitania and Zimmerman Telegram. What started the war the ruler of the ottoman empire was assassinated and what expanded the war was the Zimmerman telegram.
It was acts passed by the radical Republicans in 1867. These acts separated the south and the north
Universities would allow scientists to investigate their theories even if they contradicted Catholic teachings.
The enactment of the Clean Air Act of 1970 (1970 CAA) resulted in a major shift in the federal government's role in air pollution control. This legislation authorized the development of comprehensive federal and state regulations to limit emissions from both stationary (industrial) sources and mobile sources.
There were lots of foreign changes that presented challenges for the US. I'll give you a few examples from different time periods. First would be when England wanted to tax the Americans in the Revolutionary period. They did this to try and restrict America's freedom. Another example would be that Russia had spies during the cold war period. This was to gain intelligence of the US war plans. Also when Germany sent the Zimmerman Telegram to Mexico during the WWII period. This was to get Mexico to launch a surprise attack on the US.
