Depending on the time period, America had a difficult time remaining neutral for several reasons.
World War I
America had a difficult time remaining neutral during World War I because of Germany's actions. For example, the German submarine sank the Lusitania, a boat that contained over 100 American citizens. Along with this, the Germans were also caught trying to make a secret alliance with Mexico. This was exposed when the Allied powers intercepted the Zimmerman Telegram. Considering these factors, the government felt the US had no choice but to break their neutrality and enter World War I.
World War II
The US had a difficult time maintaining neutral in World War II due to the violence and rise of dictators like Hitler. Along with this, the US was also attacked by the Japanese military. The Japanese military bombed Pearl Harbor on December 7, 1941. This attack on a military base prompted the US to break their policy of neutrality in order to enter World War II.
Answer:
The Air Pollution Control Act of 1955 was the first federal legislation involving air pollution
Explanation:
1519 (March 4): The Spaniards land in what is now Veracruz. The natives greet him with gifts. A contingent from Tenochtitlán also arrives with gifts. Cortes showed force and demonstrated his canons, terrifying the messengers.
Cortes sinks all the ships except one small vessel, and moves to the city-state of Tlaxcala. Generally speaking they begin on friendly terms.
The Spanish went on to Cholula. It's unclear what happened, but in the end many people in the city were killed by the Spanish.
1519 (Nov 8): Cortes and army arrives at Tenochtitlán, and begin on good terms. However, Cortes takes charge and demands tribute and some Roman Catholic shrines to replace the Aztec gods.
Cortes returns to the coast to defeat a rival Spanish army. The remaining soldiers join him.
The Aztecs revolt, driving the Spanish from the city. Cuitláhuac becomes emperor.
The Spanish go to Tlaxcala and make an alliance with them.
Most Aztec cities are conquered, and a siege of Tenochtitlán begins.
1521 (13 August): The last Aztec emperor, Cuauhtémoc, surrenders to Cortes.