Were most negatively affected by westward expansion and the new fencing methods.

Plains Indians (Plains Native Americans)

Explanation:

As the colonists moved west, they wanted more land.  They wanted to establish more cities/villages in the plains and also in the west where the Native Americans lived. The Native Americans also depending on the migration of the animals - deer, buffalo, etc. - for hunting which provided them with food and clothing. However, when the colonists moved west, they put up more fences which prevented animals from freely moving among the plains.  The fences also interrupted and changed the animal migration routes.  

since most of current immigration into the u.s., both legal and illegal, is coming from latin america. it would be very difficult to imagine or rationalize a country my fellow citizens are trying desperately to flee into, would pose a threat to my prosperity or freedom. since the u.s. has a long history of intervention, but no record of permanent occupation, i would not feel oppression is the main objective.  

the largest free trade nation, along with the largest gdp in the world wanting to expand it's economic policy on us, and including us, could only be positive. the u.s. government has no interest in, or way of simply forcing american culture on us. and has no track record of it. other nations that adopted american social culture, or "americanization" did so voluntarily, mainly through the choice of allowing american businesses and u.s. citizens to come into their nations, as free operatives.

information is crucial for making good decisions