The revolution in Haiti took place when a large portion of the islands slave population rose against their colonial masters. Many Americans were concerned that the revolt would inspire slaves in the US to do the same thing.
The belief that the United states had a duty to spread democracy across the continent.
As for material wise, the English realized that the American Colonies could provide a stable stream of funds that relied on the production, refining, and sale of many different supplies and crops. Such examples would be Tobacco, Sugar (not 100% on this one), and Cotton (later on). Other products that could be produced in the Americas were whale oil and seafood. As for influence, the English noticed that they could claim large parts of Unclaimed (and sometimes claimed, which they woukd fight for) North America such as parts of Canada and almost the entire East Coats in order to spread the influence of the Crown further throughout the world. It was also a power struggle fight between Britain, France, and Spain, which was another reason for the colonies.
Explanation:
Here's a (very) brief summary of the fall of the Aztec empire, after the arrival of Hernando Cortes until the fall of Tenochtitlán (read a biography of Hernan Cortez here):
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. Read more about Cholula here.
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.
Answer:
Crowded and unsafe living conditions.
Explanation:
Most immigrants in the early 1800s would probably be very poor, especially after spending the money to travel to an entirely new country. Most immigrants were probably escaping from corrupt governments, looking for religious freedom, or simply wanting a fresh start. They mostly travelled in big groups, either families or neighbors or small communities, and because of this, their housing was probably cramped, run down, and very quickly and poorly built to account for this influx of new people pouring into the US.