Why is the United States involved in this organization?
is it to establish a trilateral trade bloc in North America
Is NAFTA supported by both political parties??
Yes.
Republicans tend to support NAFTA, while many Democrats do not.
... and vice versa!!
how come republicans support Nafta and democrats don't
do u have any sources i can use
Start here: http://people.virginia.edu/~wjk/nafta.html
You can find more by googling problems with nafta.
"Supporters of NAFTA argue (among other things) that increased trade benefits American consumers though more competition and that free trade helps less wealthy countries improve their standard of living. Opponents of NAFTA argue (among other things) that NAFTA has encouraged the manufacturing sector to seek cheaper labor in Mexico, and has harmed American workers"
"that is has created loss of jobs, elimination of industries, and worker displacement
I suppose, although I'd want some proof of all these assertions. These are fairly general, and you should be able to provide specifics to either support or reject each assertion.
~ Have American consumers benefited since 1991? If so, how?
~ Have less wealthy countries (e.g., Mexico) improved their standard of living since 1991? Which ones? How is this measured?
~ Have some businesses moved their manufacturing to Mexico? Which ones?
~ Have American workers been harmed? If so, how?